diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,18 @@
+# 0.14.3
+- Compatibility with `lens-aeson` > 1.2
+
+# 0.14.2
+- Export the `ToARec` class
+
+# 0.14.1
+- Compatibility with `aeson` > 2.0
+
+# 0.14.0
+- `ARec` efficiency improvements (@Philonous)
+- Make `ElField` a newtype (@Philonous)
+
+The `ElField` change brings more opportunities for the optimizer, but can result in longer compile times.
+
 # 0.13.3
 - Fixed CHANGELOG entry for 0.13.2: it referred to version 0.14.0
 - Relax bounds on `hspec`
diff --git a/Data/Vinyl/ARec.hs b/Data/Vinyl/ARec.hs
--- a/Data/Vinyl/ARec.hs
+++ b/Data/Vinyl/ARec.hs
@@ -8,6 +8,7 @@
 module Data.Vinyl.ARec
   ( ARec -- Exported abstractly
   , IndexableField
+  , ToARec
   , toARec
   , fromARec
   , aget
diff --git a/Data/Vinyl/ARec/Internal.hs b/Data/Vinyl/ARec/Internal.hs
--- a/Data/Vinyl/ARec/Internal.hs
+++ b/Data/Vinyl/ARec/Internal.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE DataKinds #-}
@@ -23,9 +24,27 @@
 -- element to the head of a list, but element access is linear time;
 -- array access time is uniform, but extending the array is more
 -- slower.
+--
+-- Tradeoffs:
+--
+-- * No sharing of the spine (i.e. when you change elements in the front of the
+--   record the tail can't be re-used)
+-- * ARec requires (4 + n) words + size of the fields
+--   * 1 for the ARec constructor
+--   * 1 for the pointer to the SmallArray#
+--   * The SmallArray# has 2 words as header (1 for GC, 1 for number of elements)
+--   * 1 pointer per element to the actual data
+-- * Rec requires (2n) words + size of Fields
+--   * 1 word per (:&) constructor
+--   * 1 word for the pointer to the element
 module Data.Vinyl.ARec.Internal
   ( ARec (..)
+  , ToARec
   , IndexableField
+  , arec
+  , ARecBuilder (..)
+  , arcons
+  , arnil
   , toARec
   , fromARec
   , aget
@@ -39,28 +58,36 @@
 import Data.Vinyl.Core
 import Data.Vinyl.Lens (RecElem(..), RecSubset(..))
 import Data.Vinyl.TypeLevel
+import Data.Vinyl.ARec.Internal.SmallArray
+import Control.Monad.ST
 
-import qualified Data.Array as Array
-import qualified Data.Array.Base as BArray
-import GHC.Exts (Any)
 import Unsafe.Coerce
 #if __GLASGOW_HASKELL__ < 806
 import Data.Constraint.Forall (Forall)
 #endif
-import Data.Coerce (Coercible)
-import Data.Type.Coercion (Coercion (..))
+import Data.Type.Coercion     (Coercion (..))
+import GHC.Types
 
 -- | An array-backed extensible record with constant-time field
 -- access.
-newtype ARec (f :: k -> *) (ts :: [k]) = ARec (Array.Array Int Any)
+newtype ARec (f :: k -> *) (ts :: [k]) = ARec SmallArray
 type role ARec representational nominal
 
+-- | Get the ith element from the ARec
+unsafeIxARec
+  :: forall a k (f :: k -> *) (ts :: [k]).
+     ARec f ts
+  -> Int
+  -> a
+unsafeIxARec (ARec ar) ix = indexSmallArray ar ix
+{-# INLINE unsafeIxARec #-}
+
 -- | Given that @xs@ and @ys@ have the same length, and mapping
 -- @f@ over @xs@ and @g@ over @ys@ produces lists whose elements
 -- are pairwise 'Coercible', @ARec f xs@ and @ARec g ys@ are
 -- 'Coercible'.
 arecRepsMatchCoercion :: AllRepsMatch f xs g ys => Coercion (ARec f xs) (ARec g ys)
-arecRepsMatchCoercion = Coercion
+arecRepsMatchCoercion = unsafeCoerce (Coercion :: Coercion () ())
 
 -- | Given that @forall x. Coercible (f x) (g x)@, produce a coercion from
 -- @ARec f xs@ to @ARec g xs@. While the constraint looks a lot like
@@ -69,7 +96,7 @@
 #if __GLASGOW_HASKELL__ >= 806
 arecConsMatchCoercion ::
   (forall (x :: k). Coercible (f x) (g x)) => Coercion (ARec f xs) (ARec g xs)
-arecConsMatchCoercion = Coercion
+arecConsMatchCoercion = unsafeCoerce (Coercion :: Coercion () ())
 #else
 arecConsMatchCoercion :: forall k (f :: k -> *) (g :: k -> *) (xs :: [k]).
   Forall (Similar f g) => Coercion (Rec f xs) (Rec g xs)
@@ -78,6 +105,28 @@
 arecConsMatchCoercion = unsafeCoerce (Coercion :: Coercion (Rec f xs) (Rec f xs))
 #endif
 
+-- Using a class instead of a recursive function allows aRecValues to be
+-- completely inlined
+class ToARec (us :: [k]) where
+  aRecValues :: Rec f us -> ARecBuilder f us
+
+instance ToARec '[] where
+  aRecValues RNil = arnil
+  {-# INLINE aRecValues #-}
+
+instance ToARec us => ToARec (u ': us) where
+  aRecValues (x :& xs) = x `arcons` aRecValues xs
+  {-# INLINE aRecValues #-}
+
+-- | Convert a 'Rec' into an 'ARec' for constant-time field access.
+toARec
+  :: forall f ts.
+     (NatToInt (RLength ts), ToARec ts)
+  => Rec f ts
+  -> ARec f ts
+toARec rs = arec (aRecValues rs)
+{-# INLINE toARec #-}
+
 {-
 -- This is sensible, but the ergonomics are likely quite bad thanks to the
 -- interaction between Coercible resolution and resolution in the presence of
@@ -89,15 +138,64 @@
 arecConsMatchCoercible f = f
 -}
 
--- | Convert a 'Rec' into an 'ARec' for constant-time field access.
-toARec :: forall f ts. (NatToInt (RLength ts)) => Rec f ts -> ARec f ts
-toARec = go id
-  where go :: ([Any] -> [Any]) -> Rec f ts' -> ARec f ts
-        go acc RNil = ARec $! Array.listArray (0, n - 1) (acc [])
-        go acc (x :& xs) = go (acc . (unsafeCoerce x :)) xs
-        n = natToInt @(RLength ts)
-{-# INLINE toARec #-}
+-- | An efficient builder for ARec values
+--
+-- Use the pseudo-constructors 'arcons' and 'arnil' to construct an
+-- 'ARecBuilder' and then turn it into an 'ARec' with 'arec'
+--
+-- Example: (requires -XOverloadedLabels and )
+--
+-- > user :: ARec ElField '[ "name"   ::: String
+-- >                       , "age"    ::: Int
+-- >                       , "active" ::: Bool]
+-- > user = arec (  #name   =: "Peter"
+-- >             `arcons` #age    =: 4
+-- >             `arcons` #active =: True
+-- >             `arcons` arnil
+-- >             )
+newtype ARecBuilder f us =
+  -- A function that writes values to the correct position in the underlying array
+  -- Takes the current index
+  ARecBuilder ( forall s.
+                Int -- Index to write to
+              -> SmallMutableArray s -- Arrray to write to
+              -> ST s ()
+              )
 
+infixr 1 `arcons`
+-- | Pseudo-constructor for an ARecBuilder
+--
+-- "Cons" a field to an ARec under construction
+--
+-- See 'ARecBuilder'
+arcons :: f u -> ARecBuilder f us -> ARecBuilder f (u ': us)
+arcons !v (ARecBuilder fvs) = ARecBuilder $ \i mArr -> do
+    writeSmallArray mArr i v
+    fvs (i+1) mArr
+{-# INLINE arcons #-}
+
+-- | Pseudo-constructor for 'ARecBuilder'
+--
+-- Build an ARec without fields
+--
+-- See 'ARecBuilder'
+arnil :: ARecBuilder f '[]
+arnil = ARecBuilder $ \_i _arr -> return ()
+{-# INLINE arnil #-}
+
+-- | Turn an ARecBuilder into an ARec
+--
+-- See 'ARecBuilder'
+arec
+  :: forall k (us :: [k] ) f
+  . (NatToInt (RLength us)) =>
+      ARecBuilder f us
+  -> ARec f us
+arec (ARecBuilder fillArray) = ARec $
+  runST $ withNewSmallArray (natToInt @(RLength us))
+          $ fillArray 0
+{-# INLINE arec #-}
+
 -- | Defines a constraint that lets us index into an 'ARec' in order
 -- to produce a 'Rec' using 'fromARec'.
 class (NatToInt (RIndex t ts)) => IndexableField ts t where
@@ -107,22 +205,22 @@
 fromARec :: forall f ts.
             (RecApplicative ts, RPureConstrained (IndexableField ts) ts)
          => ARec f ts -> Rec f ts
-fromARec (ARec arr) = rpureConstrained @(IndexableField ts) aux
+fromARec ar = rpureConstrained @(IndexableField ts) aux
   where aux :: forall t. NatToInt (RIndex t ts) => f t
-        aux = unsafeCoerce (arr Array.! natToInt @(RIndex t ts))
+        aux = unsafeIxARec ar (natToInt @(RIndex t ts))
 {-# INLINE fromARec #-}
 
 -- | Get a field from an 'ARec'.
 aget :: forall t f ts. (NatToInt (RIndex t ts)) => ARec f ts -> f t
-aget (ARec arr) =
-  unsafeCoerce (BArray.unsafeAt arr (natToInt @(RIndex t ts)))
+aget ar = unsafeIxARec ar (natToInt @(RIndex t ts))
 {-# INLINE aget #-}
 
 -- | Set a field in an 'ARec'.
 unsafeAput :: forall t t' f ts ts'. (NatToInt (RIndex t ts))
       => f t' -> ARec f ts -> ARec f ts'
-unsafeAput x (ARec arr) = ARec (arr Array.// [(i, unsafeCoerce x)])
-  where i = natToInt @(RIndex t ts)
+unsafeAput x (ARec arr) = ARec $ runST $
+  withThawedSmallArray arr $ \mArr ->
+    writeSmallArray mArr (natToInt @(RIndex t ts)) x
 {-# INLINE unsafeAput #-}
 
 -- | Define a lens for a field of an 'ARec'.
@@ -157,19 +255,31 @@
 arecGetSubset :: forall rs ss f.
                  (IndexWitnesses (RImage rs ss), NatToInt (RLength rs))
               => ARec f ss -> ARec f rs
-arecGetSubset (ARec arr) = ARec (Array.listArray (0, n-1) $
-                                 go (indexWitnesses @(RImage rs ss)))
-  where go :: [Int] -> [Any]
-        go = map (arr Array.!)
-        n = natToInt @(RLength rs)
+arecGetSubset (ARec arr) =
+  ARec $ runST $
+    withNewSmallArray (natToInt @(RLength rs)) $ \mArr ->
+      go mArr 0 (indexWitnesses @(RImage rs ss))
+  where
+    go :: SmallMutableArray s -> Int -> [Int] -> ST s ()
+    go _mArr _to [] = return ()
+    go mArr to (from : froms) = do
+      writeSmallArray mArr to (indexSmallArray arr from :: Any)
+      go mArr (to + 1) froms
 {-# INLINE arecGetSubset #-}
 
 -- | Set a subset of a larger record's fields to all of the fields of
 -- a smaller record.
 arecSetSubset :: forall rs ss f. (IndexWitnesses (RImage rs ss))
               => ARec f ss -> ARec f rs -> ARec f ss
-arecSetSubset (ARec arrBig) (ARec arrSmall) = ARec (arrBig Array.// updates)
-  where updates = zip (indexWitnesses @(RImage rs ss)) (Array.elems arrSmall)
+arecSetSubset (ARec arrBig) (ARec arrSmall) = ARec $ runST $
+  withThawedSmallArray arrBig $ \mArr -> do
+    go mArr 0 (indexWitnesses @(RImage rs ss))
+  where
+    go :: SmallMutableArray s -> Int -> [Int] -> ST s ()
+    go _mArr _ [] = return ()
+    go mArr from (to : tos) = do
+      writeSmallArray mArr to (indexSmallArray arrSmall from)
+      go mArr (from + 1) tos
 {-# INLINE arecSetSubset #-}
 
 instance (is ~ RImage rs ss, IndexWitnesses is, NatToInt (RLength rs))
diff --git a/Data/Vinyl/ARec/Internal/SmallArray.hs b/Data/Vinyl/ARec/Internal/SmallArray.hs
new file mode 100644
--- /dev/null
+++ b/Data/Vinyl/ARec/Internal/SmallArray.hs
@@ -0,0 +1,56 @@
+{-# LANGUAGE MagicHash #-}
+{-# LANGUAGE UnboxedTuples #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE BangPatterns #-}
+
+-- | Helper functions for SmallArray#
+--
+-- This module exposes _unsafe_ functions to work with SmallArrays.  That means
+-- that specifically neither index bounds nor element types are checked So this
+-- functionality should only be used in a context that enforces them by some
+-- other means, e.g. ARec's type index
+
+module Data.Vinyl.ARec.Internal.SmallArray where
+
+import GHC.Prim
+import GHC.Types
+import Unsafe.Coerce
+import GHC.ST
+
+data SmallArray = SmallArray !(SmallArray# Any)
+data SmallMutableArray s = SmallMutableArray !(SmallMutableArray# s Any)
+
+indexSmallArray :: SmallArray -> Int -> a
+indexSmallArray (SmallArray arr) (I# ix) =
+  case indexSmallArray# arr ix of
+    (# v #) -> unsafeCoerce v
+{-# INLINE indexSmallArray #-}
+
+withNewSmallArray :: Int -> (SmallMutableArray s -> ST s ()) -> ST s SmallArray
+withNewSmallArray (I# len#) f =
+  ST $ \s0 ->  case newSmallArray# len# (error "withNewSmallArray exploded") s0 of
+       (# s1, mArr #) ->
+         case f (SmallMutableArray mArr) of
+           ST st -> case st s1 of
+             (# s2, () #) -> case unsafeFreezeSmallArray# mArr s2 of
+               (# s3, ar #) -> (# s3, SmallArray ar #)
+{-# INLINE withNewSmallArray #-}
+
+writeSmallArray :: SmallMutableArray s -> Int -> a -> ST s ()
+writeSmallArray (SmallMutableArray mArr) (I# n#) x = ST $ \s ->
+  case writeSmallArray# mArr n# (unsafeCoerce x) s of
+    s' -> (# s', () #)
+{-# INLINE writeSmallArray #-}
+
+withThawedSmallArray :: SmallArray
+               -> (SmallMutableArray s -> ST s ())
+               -> ST s SmallArray
+withThawedSmallArray (SmallArray arr) f = ST $ \s0 ->
+  let !(I# z#) = 0
+  in case thawSmallArray# arr z# (sizeofSmallArray# arr) s0 of
+       (# s1, mArr #) ->
+         case f (SmallMutableArray mArr) of
+           ST st -> case st s1 of
+             (# s2, () #) -> case unsafeFreezeSmallArray# mArr s2 of
+               (# s3, ar #) -> (# s3, SmallArray ar #)
+{-# INLINE withThawedSmallArray #-}
diff --git a/Data/Vinyl/Class/Method.hs b/Data/Vinyl/Class/Method.hs
--- a/Data/Vinyl/Class/Method.hs
+++ b/Data/Vinyl/Class/Method.hs
@@ -142,7 +142,7 @@
 -- | The interpretation function of the 'FieldTyper' symbols.
 type family ApplyFieldTyper (f :: FieldTyper) (a :: k) :: * where
   ApplyFieldTyper 'FieldId a = a
-  ApplyFieldTyper 'FieldSnd '(s, b) = b
+  ApplyFieldTyper 'FieldSnd a = Snd a
 
 -- | A mapping of record contexts into the 'FieldTyper' function
 -- space. We explicitly match on 'ElField' to pick out the payload
diff --git a/Data/Vinyl/Curry.hs b/Data/Vinyl/Curry.hs
--- a/Data/Vinyl/Curry.hs
+++ b/Data/Vinyl/Curry.hs
@@ -11,7 +11,7 @@
 
 -}
 module Data.Vinyl.Curry where
-
+import           Data.Kind (Type)
 import           Data.Vinyl
 import           Data.Vinyl.Functor
 import           Data.Vinyl.XRec
@@ -170,7 +170,7 @@
 CurriedF Maybe '[Int, Bool, String] Int :: *
 = Maybe Int -> Maybe Bool -> Maybe [Char] -> Int
 -}
-type family CurriedF (f :: u -> *) (ts :: [u]) a where
+type family CurriedF (f :: u -> Type) (ts :: [u]) a where
   CurriedF f '[] a = a
   CurriedF f (t ': ts) a = f t -> CurriedF f ts a
 
@@ -183,6 +183,6 @@
 CurriedX (Maybe :. Identity) '[Int, Bool, String] Int :: *
 = Maybe Int -> Maybe Bool -> Maybe [Char] -> Int
 -}
-type family CurriedX (f :: u -> *) (ts :: [u]) a where
+type family CurriedX (f :: u -> Type) (ts :: [u]) a where
   CurriedX f '[] a = a
   CurriedX f (t ': ts) a = HKD f t -> CurriedX f ts a
diff --git a/Data/Vinyl/Derived.hs b/Data/Vinyl/Derived.hs
--- a/Data/Vinyl/Derived.hs
+++ b/Data/Vinyl/Derived.hs
@@ -46,7 +46,7 @@
 getField (Field x) = x
 
 -- | Get the label name of an 'ElField'.
-getLabel :: forall s t. ElField '(s,t) -> String
+getLabel :: forall s t. KnownSymbol s => ElField '(s,t) -> String
 getLabel (Field _) = symbolVal (Proxy::Proxy s)
 
 -- | 'ElField' is isomorphic to a functor something like @Compose
diff --git a/Data/Vinyl/FromTuple.hs b/Data/Vinyl/FromTuple.hs
--- a/Data/Vinyl/FromTuple.hs
+++ b/Data/Vinyl/FromTuple.hs
@@ -14,6 +14,7 @@
 -- example record construction using 'ElField' for named fields:
 -- @fieldRec (#x =: True, #y =: 'b') :: FieldRec '[ '("x", Bool), '("y", Char) ]@
 module Data.Vinyl.FromTuple where
+import Data.Kind (Type)
 import Data.Monoid (First(..))
 #if __GLASGOW_HASKELL__ < 804
 import Data.Semigroup (Semigroup(..))
@@ -29,7 +30,7 @@
 -- type constructor to a tuple of the common type constructor and a
 -- list of the types to which it is applied in the original
 -- tuple. E.g. @TupleToRecArgs f (f a, f b) ~ (f, [a,b])@.
-type family TupleToRecArgs f t = (r :: (u -> *, [u])) | r -> t where
+type family TupleToRecArgs f t = (r :: (u -> Type, [u])) | r -> t where
   TupleToRecArgs f (f a, f b, f c, f d, f e, f z, f g, f h) =
     '(f, [a,b,c,d,e,z,g,h])
   TupleToRecArgs f (f a, f b, f c, f d, f e, f z, f g) = '(f, [a,b,c,d,e,z,g])
@@ -42,12 +43,12 @@
 
 -- | Apply the 'Rec' type constructor to a type-level tuple of its
 -- arguments.
-type family UncurriedRec (t :: (u -> *, [u])) = r | r -> t where
+type family UncurriedRec (t :: (u -> Type, [u])) = r | r -> t where
   UncurriedRec '(f, ts) = Rec f ts
 
 -- | Apply the 'XRec' type constructor to a type-level tuple of its
 -- arguments.
-type family UncurriedXRec (t :: (u -> *, [u])) = r | r -> t where
+type family UncurriedXRec (t :: (u -> Type, [u])) = r | r -> t where
   UncurriedXRec '(f, ts) = XRec f ts
 
 -- | Convert between an 'XRec' and an isomorphic tuple.
@@ -90,7 +91,7 @@
     (a, b, c, d, e, z, g, h)
   xrecX (a, b, c, d, e, z, g, h) = a ::& b ::& c ::& d ::& e ::& z ::& g ::& h ::& XRNil
 
-type family ListToHKDTuple (f :: u -> *) (ts :: [u]) :: * where
+type family ListToHKDTuple (f :: u -> Type) (ts :: [u]) :: Type where
   ListToHKDTuple f '[] = HKD f ()
   ListToHKDTuple f '[a,b] = (HKD f a, HKD f b)
   ListToHKDTuple f '[a,b,c] = (HKD f  a, HKD f b, HKD f c)
diff --git a/Data/Vinyl/Functor.hs b/Data/Vinyl/Functor.hs
--- a/Data/Vinyl/Functor.hs
+++ b/Data/Vinyl/Functor.hs
@@ -42,6 +42,7 @@
 import GHC.Generics
 import GHC.TypeLits
 import GHC.Types (Type)
+import Data.Vinyl.TypeLevel (Snd)
 
 {- $introduction
     This module provides functors and functor compositions
@@ -107,8 +108,10 @@
 -- | A value with a phantom 'Symbol' label. It is not a
 -- Haskell 'Functor', but it is used in many of the same places a
 -- 'Functor' is used in vinyl.
-data ElField (field :: (Symbol, Type)) where
-  Field :: KnownSymbol s => !t -> ElField '(s,t)
+--
+-- Morally: newtype ElField (s, t) = Field t
+-- But GHC doesn't allow that
+newtype ElField (t :: (Symbol, Type)) = Field (Snd t)
 
 deriving instance Eq t => Eq (ElField '(s,t))
 deriving instance Ord t => Ord (ElField '(s,t))
diff --git a/Data/Vinyl/Syntax.hs b/Data/Vinyl/Syntax.hs
--- a/Data/Vinyl/Syntax.hs
+++ b/Data/Vinyl/Syntax.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, FlexibleInstances, InstanceSigs,
+{-# LANGUAGE CPP, FlexibleContexts, FlexibleInstances, InstanceSigs,
              MultiParamTypeClasses, ScopedTypeVariables,
              TypeApplications, TypeFamilies, TypeOperators,
              UndecidableInstances #-}
diff --git a/Data/Vinyl/TypeLevel.hs b/Data/Vinyl/TypeLevel.hs
--- a/Data/Vinyl/TypeLevel.hs
+++ b/Data/Vinyl/TypeLevel.hs
@@ -73,7 +73,7 @@
   RImage '[] ss = '[]
   RImage (r ': rs) ss = RIndex r ss ': RImage rs ss
 
--- | Remove the first occurence of a type from a type-level list.
+-- | Remove the first occurrence of a type from a type-level list.
 type family RDelete r rs where
   RDelete r (r ': rs) = rs
   RDelete r (s ': rs) = s ': RDelete r rs
diff --git a/benchmarks/AccessorsBench.hs b/benchmarks/AccessorsBench.hs
--- a/benchmarks/AccessorsBench.hs
+++ b/benchmarks/AccessorsBench.hs
@@ -8,21 +8,12 @@
 import Data.Monoid (Endo(..))
 import           Data.Vinyl
 import           Data.Vinyl.Syntax ()
-import Lens.Micro ((%~), (&))
-import           System.Exit (exitFailure)
-
-type Fields = '[ '( "a0", Int ), '( "a1", Int ), '( "a2", Int ), '( "a3", Int )
-               , '( "a4", Int ), '( "a5", Int ), '( "a6", Int ), '( "a7", Int )
-               , '( "a8", Int ), '( "a9", Int ), '( "a10", Int ), '( "a11", Int )
-               , '( "a12", Int ), '( "a13", Int ), '( "a14", Int ), '( "a15", Int )
-               ]
+import           Lens.Micro        ((%~), (&))
+import           System.Exit       (exitFailure)
 
-newF :: FieldRec Fields
-newF = Field 0 :& Field 0 :& Field 0 :& Field 0 :&
-       Field 0 :& Field 0 :& Field 0 :& Field 0 :&
-       Field 0 :& Field 0 :& Field 0 :& Field 0 :&
-       Field 0 :& Field 0 :& Field 0 :& Field 99 :&
-       RNil
+import           Bench.ARec
+import           Bench.SRec
+import           Bench.Rec
 
 data HaskRec = HaskRec {
   a0 :: Int,
@@ -45,6 +36,10 @@
 haskRec :: HaskRec
 haskRec = HaskRec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 99
 
+sumHaskRec r =
+    a0 r + a1 r + a2 r + a3 r + a4 r + a5 r + a6 r + a7 r + a8 r + a9 r
+  + a10 r + a11 r + a12 r + a13 r + a14 r + a15 r
+
 data StrictHaskRec = StrictHaskRec {
   sa0 :: !Int,
   sa1 :: !Int,
@@ -66,6 +61,10 @@
 shaskRec :: StrictHaskRec
 shaskRec = StrictHaskRec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 99
 
+sumSHaskRec r =
+    sa0 r + sa1 r + sa2 r + sa3 r + sa4 r + sa5 r + sa6 r + sa7 r + sa8 r + sa9 r
+  + sa10 r + sa11 r + sa12 r + sa13 r + sa14 r + sa15 r
+
 data UStrictHaskRec = UStrictHaskRec {
   usa0 :: {-# UNPACK #-} !Int,
   usa1 :: {-# UNPACK #-} !Int,
@@ -87,6 +86,10 @@
 ushaskRec :: UStrictHaskRec
 ushaskRec = UStrictHaskRec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 99
 
+sumUSHaskRec r =
+    usa0 r + usa1 r + usa2 r + usa3 r + usa4 r + usa5 r + usa6 r + usa7 r + usa8 r
+    + usa9 r + usa10 r + usa11 r + usa12 r + usa13 r + usa14 r + usa15 r
+
 type SubFields = '[ '("a0", Int), '("a8", Int), '("a15", Int)]
 
 -- updateSRec :: forall record. RecordSubset record ElField SubFields Fields
@@ -115,7 +118,8 @@
 
 main :: IO ()
 main =
-  do let arec = toARec newF
+  do let newF = mkRec 0
+         arec = toARec newF
          srec = toSRec newF
      unless (rvalf #a15 arec == rvalf #a15 newF)
             (do putStrLn "AFieldRec accessor disagrees with rvalf"
@@ -142,7 +146,22 @@
          , bench "ARec" $ nf (rvalf #a15 . updateARec) arec
          , bench "SRec" $ nf (rvalf #a15 . updateSRec) srec
          ]
-         , bgroup "FieldRec"
+         ,
+         bgroup "creating"
+         [ bench "vinyl record" $ whnf mkRec 0
+         , bench "toSRec" $ whnf mkToSRec 0
+         , bench "New style ARec with toARec " $ whnf mkToARec 0
+         , bench "New style ARec with arec " $ whnf mkARec 0
+         ]
+         ,bgroup "sums"
+         [ bench "haskell record" $ nf sumHaskRec haskRec
+         , bench "strict haskell record" $ whnf sumSHaskRec shaskRec
+         , bench "unboxed strict haskell record" $ whnf sumUSHaskRec ushaskRec
+         , bench "vinyl SRec" $ nf sumSRec srec
+         , bench "vinyl Rec" $ nf sumRec newF
+         , bench "vinyl ARec" $ nf sumARec arec
+         ]
+       , bgroup "FieldRec"
          [ bench "a0" $ nf (rvalf #a0) newF
          , bench "a4" $ nf (rvalf #a4) newF
          , bench "a8" $ nf (rvalf #a8) newF
diff --git a/benchmarks/Bench/ARec.hs b/benchmarks/Bench/ARec.hs
new file mode 100644
--- /dev/null
+++ b/benchmarks/Bench/ARec.hs
@@ -0,0 +1,39 @@
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE OverloadedLabels      #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE GADTs #-}
+
+module Bench.ARec where
+
+import Data.Vinyl
+import Data.Vinyl.ARec.Internal
+import Data.Vinyl.Syntax ()
+
+import Bench.Rec
+
+mkARec :: Int -> ARec ElField Fields
+mkARec i= arec (Field i `arcons` Field i `arcons` Field i `arcons` Field i `arcons`
+                  Field i `arcons` Field i `arcons` Field i `arcons` Field i `arcons`
+                  Field i `arcons` Field i `arcons` Field i `arcons` Field i `arcons`
+                  Field i `arcons` Field i `arcons` Field i `arcons` Field 99 `arcons`
+                  arnil)
+
+
+mkToARec :: Int -> ARec ElField Fields
+mkToARec i= toARec (Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field 99 :&
+                  RNil)
+
+sumARec :: ARec ElField Fields -> Int
+sumARec str =
+    get #a0 str + get #a1 str + get #a2 str + get #a3 str + get #a4 str
+  + get #a5 str + get #a6 str + get #a7 str + get #a8 str
+  + get #a9 str + get #a10 str + get #a11 str + get #a12 str
+  + get #a13 str + get #a14 str + get #a15 str
+  where
+    get label r = rvalf label r
+    {-# INLINE get #-}
diff --git a/benchmarks/Bench/Rec.hs b/benchmarks/Bench/Rec.hs
new file mode 100644
--- /dev/null
+++ b/benchmarks/Bench/Rec.hs
@@ -0,0 +1,37 @@
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE OverloadedLabels      #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE GADTs #-}
+
+module Bench.Rec where
+
+import           Data.Vinyl
+import           Data.Vinyl.Syntax ()
+
+
+type Fields = '[ '( "a0", Int ), '( "a1", Int ), '( "a2", Int ), '( "a3", Int )
+               , '( "a4", Int ), '( "a5", Int ), '( "a6", Int ), '( "a7", Int )
+               , '( "a8", Int ), '( "a9", Int ), '( "a10", Int ), '( "a11", Int )
+               , '( "a12", Int ), '( "a13", Int ), '( "a14", Int ), '( "a15", Int )
+               ]
+
+mkRec :: Int -> Rec ElField Fields
+mkRec i= Field i :& Field i :& Field i :& Field i :&
+         Field i :& Field i :& Field i :& Field i :&
+         Field i :& Field i :& Field i :& Field i :&
+         Field i :& Field i :& Field i :& Field 99 :&
+         RNil
+
+sumRec :: Rec ElField Fields -> Int
+sumRec str =
+    get #a0 str + get #a1 str + get #a2 str + get #a3 str + get #a4 str
+  + get #a5 str + get #a6 str + get #a7 str + get #a8 str
+  + get #a9 str + get #a10 str + get #a11 str + get #a12 str
+  + get #a13 str + get #a14 str + get #a15 str
+  where
+    get (_label :: Label s) r =
+      let (Field v) = rget @'(s, _) r
+      in v
+    {-# INLINE get #-}
diff --git a/benchmarks/Bench/SRec.hs b/benchmarks/Bench/SRec.hs
new file mode 100644
--- /dev/null
+++ b/benchmarks/Bench/SRec.hs
@@ -0,0 +1,34 @@
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE OverloadedLabels      #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE GADTs #-}
+
+module Bench.SRec where
+
+import Data.Vinyl.SRec
+import Data.Vinyl
+
+import Bench.Rec (Fields)
+
+
+mkToSRec :: Int -> SRec ElField Fields
+mkToSRec i= toSRec (Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field i :&
+                  Field i :& Field i :& Field i :& Field 99 :&
+                  RNil)
+
+
+sumSRec :: SRec ElField Fields -> Int
+sumSRec str =
+    get #a0 str + get #a1 str + get #a2 str + get #a3 str + get #a4 str
+  + get #a5 str + get #a6 str + get #a7 str + get #a8 str
+  + get #a9 str + get #a10 str + get #a11 str + get #a12 str
+  + get #a13 str + get #a14 str + get #a15 str
+  where
+    get (label :: Label s) r =
+      case rget @'(s, Int) r of
+        Field v -> v
+    {-# INLINE get #-}
diff --git a/tests/Aeson.hs b/tests/Aeson.hs
--- a/tests/Aeson.hs
+++ b/tests/Aeson.hs
@@ -48,11 +48,42 @@
 import Data.Vinyl.Functor (Compose(..), (:.), Identity(..), Const(..))
 import Data.Aeson
 import Data.Aeson.Encoding.Internal (wrapObject, pair)
+#if MIN_VERSION_aeson(2,0,0)
+import Control.Lens (_1, (%~))
+import qualified Data.Aeson.Key as Key
+import qualified Data.Aeson.KeyMap as KeyMap
+#endif
 import Data.Aeson.Lens (_Object)
 import GHC.Generics (Generic, Rep)
 import GHC.TypeLits (KnownSymbol)
 import Test.Hspec
 
+-- * Compatibility with aeson < 2
+#if MIN_VERSION_aeson(2,0,0)
+type KeyMap = KeyMap.KeyMap Value
+
+keyFromString :: String -> Key
+keyFromString = Key.fromString
+
+keyFromText :: Text -> Key
+keyFromText = Key.fromText
+
+keyMapToList :: KeyMap -> [(Key,Value)]
+keyMapToList = KeyMap.toList
+#else
+type Key = Text
+type KeyMap = H.HashMap Text Value
+
+keyFromString :: String -> Key
+keyFromString = T.pack
+
+keyFromText :: Text -> Key
+keyFromText = id
+
+keyMapToList :: KeyMap -> [(Key,Value)]
+keyMapToList = H.toList
+#endif
+
 -- * Implementing 'ToJSON' for 'Rec'
 
 -- | An 'Identity' functor is not reflected in a value's JSON
@@ -62,23 +93,23 @@
 
 -- | A named field serializes to a JSON object with a single named
 -- field.
-instance ToJSON a => ToJSON (ElField '(s,a)) where
-  toJSON x = object [(T.pack (getLabel x), toJSON (getField x))]
+instance (KnownSymbol s, ToJSON a) => ToJSON (ElField '(s,a)) where
+  toJSON x = object [(keyFromString (getLabel x), toJSON (getField x))]
 
 -- | A @((Text,) :. f) a@ value maps to a JSON field whose name is the
 -- 'Text' value, and whose value has type @f a@.
 instance ToJSON (f a) => ToJSON ((((,) Text) :. f) a) where
-  toJSON (Compose (name, x)) = object [(name, toJSON x)]
+  toJSON (Compose (name, x)) = object [(keyFromText name, toJSON x)]
 
 -- | Replace each field of a record with the result of serializing it
 -- to a JSON 'Value', and then extracting that 'Value''s single named
 -- field. If the serialization is not in the form of an object with a
 -- single field, the conversion fails with a 'Nothing'.
 fieldsToJSON :: (RecMapMethod1 ToJSON f rs)
-             => Rec f rs -> Rec (Maybe :. Const (Text,Value)) rs
+             => Rec f rs -> Rec (Maybe :. Const (Key,Value)) rs
 fieldsToJSON = rmapMethod1 @ToJSON (Compose . aux)
   where aux x = case toJSON x of
-                  Object (H.toList -> [field]) -> Just (Const field)
+                  Object (keyMapToList -> [field]) -> Just (Const field)
                   _ -> Nothing
 
 -- | Convert a homogeneous record to a list factored through an outer
@@ -176,19 +207,21 @@
 -- loses precision in the type.
 class ToJSONField a where
   encodeJSONField :: a -> Series
-  toJSONField :: a -> (Text,Value)
+  toJSONField :: a -> (Key,Value)
 
 -- | An @ElField '(s,a)@ value maps to a JSON field with name @s@ and
 -- value @a@.
 instance (ToJSON a, KnownSymbol s) => ToJSONField (ElField '(s,a)) where
-  encodeJSONField x = pair (T.pack (getLabel x)) (toEncoding (getField x))
-  toJSONField x = (T.pack (getLabel x), toJSON (getField x))
+  encodeJSONField x = pair (keyFromString (getLabel x))
+                           (toEncoding (getField x))
+  toJSONField x = (keyFromString (getLabel x), toJSON (getField x))
 
 -- | A @((Text,) :. f) a@ value maps to a JSON field whose name is the
 -- 'Text' value, and whose value has type @f a@.
 instance ToJSON (f a) => ToJSONField (((,) Text :. f) a) where
-  encodeJSONField (Compose (name,val)) = pair name (toEncoding val)
-  toJSONField (Compose (name,val)) = (name, toJSON val)
+  encodeJSONField (Compose (name,val)) =
+    pair (keyFromText name) (toEncoding val)
+  toJSONField (Compose (name,val)) = (keyFromText name, toJSON val)
 
 encodeRec :: (RFoldMap rs, RecMapMethod1 ToJSONField f rs)
           => Rec f rs -> Encoding
@@ -207,7 +240,7 @@
 
 -- | If a 'Value' is a nested 'Array' of 'Object's, extract the
 -- collection of key-value pairs from the entire recursive structure.
-allAesonFields :: Value -> Maybe (H.HashMap Text Value)
+allAesonFields :: Value -> Maybe Object
 allAesonFields (Array arr) =
   case V.toList arr of
     [] -> Just mempty
@@ -224,8 +257,19 @@
 
 -- | A lens implementation of something a bit looser than
 -- 'unnestFields'.
-allFields :: Value -> H.HashMap Text Value
+allFields :: Value -> Object
+#if MIN_VERSION_aeson(2,0,0)
+allFields = KeyMap.fromList
+#if MIN_VERSION_lens_aeson(1,2,0)
+          . keyMapToList
+#else
+          . map (_1 %~ Key.fromText)
+          . H.toList
+#endif
+          . view (deep _Object)
+#else
 allFields = view (deep _Object)
+#endif
 
 -- | The generic 'ToJSON' instance is not quite right since we use the
 -- record's interpretation type constructor to define serialization,
diff --git a/tests/Spec.hs b/tests/Spec.hs
--- a/tests/Spec.hs
+++ b/tests/Spec.hs
@@ -11,6 +11,8 @@
 import qualified CoRecSpec as C
 import qualified XRecSpec as X
 
+import qualified Test.ARec as ARec
+
 -- d1 :: FieldRec '[ '("X",String), '("Y", String) ]
 -- d1 = Field @"X" "5" :& Field @"Y" "Hi" :& RNil
 
@@ -71,3 +73,5 @@
       (#x .~ 2.1) d3 `shouldBe` fieldRec (#x =: 2.1, #y =: "Hi")
     it "Can change a field's type" $
       (d3 & #y %~ length) `shouldBe` fieldRec (#x =: 5, #y =: 2)
+
+  ARec.spec
diff --git a/tests/Test/ARec.hs b/tests/Test/ARec.hs
new file mode 100644
--- /dev/null
+++ b/tests/Test/ARec.hs
@@ -0,0 +1,101 @@
+{-# LANGUAGE DataKinds, FlexibleContexts, GADTs,
+             NoMonomorphismRestriction, OverloadedLabels,
+             ScopedTypeVariables, TypeApplications, TypeOperators #-}
+{-# OPTIONS_GHC -Wall -Wno-type-defaults #-}
+
+module Test.ARec where
+
+import Data.Vinyl.ARec
+import Data.Vinyl
+import Test.Hspec
+
+import Data.Vinyl.Syntax ()
+
+type FullARec = ARec ElField '[ "f0" ::: Int , "f1" ::: Bool , "f2" ::: String
+                              , "f3" ::: Double, "f4" ::: Integer
+                              , "f2" ::: Int -- intentionally duplicate field name
+                              ]
+
+type SubARecPre = ARec ElField '[ "f0" ::: Int , "f1" ::: Bool , "f2" ::: String ]
+
+type SubARecDupes = ARec ElField '[ "f2" ::: String, "f2" ::: String
+                                  , "f2" ::: Int, "f2" ::: String
+                                  ]
+
+
+fullARec :: FullARec
+fullARec = toARec ( #f0 =: 1 :& #f1 =: False :& #f2 =: "field2"
+                  :& #f3 =: 3.1415 :& #f4 =: 4444
+                  :& #f2 =: 666
+                  :& RNil
+                  )
+
+-- For arecGetSubset -----------------------------------------------------------
+
+subARecPre :: SubARecPre
+subARecPre = toARec ( #f0 =: 1 :& #f1 =: False :& #f2 =: "field2" :&  RNil)
+
+subARecDupes :: SubARecDupes
+subARecDupes = toARec ( #f2 =: "field2" :& #f2 =: "field2"
+                        :& #f2 =: 666 :& #f2 =: "field2"
+                        :& RNil
+                      )
+
+arecWithDupes :: ARec ElField '[ "f" ::: Int, "f" ::: Int]
+arecWithDupes = toARec (#f =: 1 :& #f =: 2 :& RNil)
+
+-- For arecSetSubset -----------------------------------------------------------
+
+subARecPreSet :: SubARecPre
+subARecPreSet = toARec ( #f0 =: 11 :& #f1 =: True :& #f2 =: "field2-updated" :&  RNil)
+
+fullARecUpdated :: FullARec
+fullARecUpdated = toARec ( #f0 =: 11 :& #f1 =: True :& #f2 =: "field2-updated"
+                           :& #f3 =: 3.1415 :& #f4 =: 4444
+                           :& #f2 =: 666
+                           :& RNil
+                         )
+
+updateARecWithDupes :: ARec ElField '[ '("f0", Int), '("f0", Int), '("f0", Int)]
+updateARecWithDupes = toARec (#f0 =: 3 :& #f0 =: 66 :& #f0 =: 1 :&RNil)
+
+subARecDupesUpdated :: SubARecDupes
+subARecDupesUpdated = toARec ( #f2 =: "updated" :& #f2 =: "field2"
+                               :& #f2 =: 666 :& #f2 =: "field2"
+                               :& RNil
+                             )
+
+
+
+spec :: SpecWith ()
+spec = describe "ARec" $ do
+  describe "arecGetSubset" $ do
+    it "retrieves a prefix ARec" $
+      -- The part to be retrieved is type-directed
+      arecGetSubset fullARec `shouldBe` subARecPre
+    it "retrieves the full ARec" $ do
+      -- Should catch off-by-one errors that lead to overflow
+      arecGetSubset fullARec `shouldBe` fullARec
+    it "handles an empty subARec correctly" $
+      arecGetSubset fullARec `shouldBe` toARec RNil
+    it "handles duplicate field names correctly in the sub arec" $
+      arecGetSubset fullARec `shouldBe` subARecDupes
+    it "handles duplicate field names correctly in the source arec" $
+      -- When both the name and the type of the field match we retrieve from the
+      -- first field
+      arecGetSubset arecWithDupes `shouldBe` toARec (#f =: (1 :: Int) :& RNil)
+  describe "arecSetSubset" $ do
+    it "sets a subset of fields" $ do
+      arecSetSubset fullARec subARecPreSet `shouldBe` fullARecUpdated
+    it "handles updates to every field" $ do
+      -- Should catch off-by-one errors that lead to overflow
+      arecSetSubset fullARec fullARec `shouldBe` fullARec
+    it "handles an empty subset" $ do
+      arecSetSubset fullARec (toARec RNil) `shouldBe` fullARec
+    it "handles duplicates in the updating ARec" $ do
+      -- The behaviour here should be that the _last_ updating field prevails
+      arecSetSubset fullARec updateARecWithDupes `shouldBe` fullARec
+    it "handles updatees with duplicate fields" $ do
+      -- Here, only the _first_ field should be updated
+      arecSetSubset subARecDupes (toARec (#f2 =: "updated" :& RNil))
+        `shouldBe` subARecDupesUpdated
diff --git a/vinyl.cabal b/vinyl.cabal
--- a/vinyl.cabal
+++ b/vinyl.cabal
@@ -1,5 +1,5 @@
 name:                vinyl
-version:             0.13.3
+version:             0.14.3
 synopsis:            Extensible Records
 -- description:
 license:             MIT
@@ -12,7 +12,7 @@
 build-type:          Simple
 cabal-version:       >=1.10
 extra-source-files:  CHANGELOG.md
-tested-with:         GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.4, GHC == 8.10.4, GHC == 9.0.1
+tested-with:         GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.4, GHC == 8.10.4, GHC == 9.0.1, GHC == 9.2.1
 
 description: Extensible records for Haskell with lenses.
 
@@ -24,6 +24,7 @@
   exposed-modules:     Data.Vinyl
                      , Data.Vinyl.ARec
                      , Data.Vinyl.ARec.Internal
+                     , Data.Vinyl.ARec.Internal.SmallArray
                      , Data.Vinyl.Class.Method
                      , Data.Vinyl.Core
                      , Data.Vinyl.CoRec
@@ -78,6 +79,9 @@
   hs-source-dirs:   benchmarks
   main-is:          AccessorsBench.hs
   build-depends:    base, criterion, tagged, vinyl, microlens
+  other-modules:    Bench.ARec
+                    Bench.SRec
+                    Bench.Rec
   ghc-options:      -O2
   default-language: Haskell2010
 
@@ -113,7 +117,9 @@
   type:                exitcode-stdio-1.0
   hs-source-dirs:      tests
   main-is:             Spec.hs
-  other-modules:       CoRecSpec XRecSpec
+  other-modules:       CoRecSpec
+                       XRecSpec
+                       Test.ARec
   build-depends:       base
                      , vinyl
                      , microlens