diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+1.0.2
+
+- [Fix performance of `argsSettings`](https://github.com/MercuryTechnologies/hlint-plugin/pull/13)
+  - Before this change `hlint-plugin` would read in the hlint settings file for
+    each Haskell module that was compiled and now it correctly caches those
+    reads, which greatly improves the performance of the plugin.
+- Small improvements to package description
+
 1.0.1
 
 - Small improvements to package description
diff --git a/hlint-plugin.cabal b/hlint-plugin.cabal
--- a/hlint-plugin.cabal
+++ b/hlint-plugin.cabal
@@ -1,9 +1,9 @@
 cabal-version:      3.0
 name:               hlint-plugin
-version:            1.0.1
+version:            1.0.2
 synopsis:           GHC plugin for hlint
 description:
-    This package provides an GHC plugin that runs `hlint` on the compiled
+    This package provides a GHC plugin that runs `hlint` on the compiled
     module.  The main advantages of doing this are: (A) better integration with
     GHC tooling, (B) only linting modules that change, and (C) only parsing the
     module once.
@@ -32,16 +32,16 @@
     if impl(ghc >= 9.0 && < 9.2)
         hs-source-dirs: ghc90
         build-depends: hlint >= 3.3   && < 3.4
-                     , ghc   >= 9.0.2 && < 9.2
+                     , ghc   >= 9.0   && < 9.2
     if impl(ghc >= 9.2 && < 9.4)
         hs-source-dirs: ghc92
         build-depends: hlint >= 3.4   && < 3.5
-                     , ghc   >= 9.2.1 && < 9.4
+                     , ghc   >= 9.2   && < 9.4
     if impl(ghc >= 9.4 && < 9.6)
         hs-source-dirs: ghc94
         build-depends: hlint >= 3.5   && < 3.6
-                     , ghc   >= 9.4.1 && < 9.6
+                     , ghc   >= 9.4   && < 9.6
     if impl(ghc >= 9.6 && < 9.8)
         hs-source-dirs: ghc96
         build-depends: hlint >= 3.6   && < 3.7
-                     , ghc   >= 9.6.1 && < 9.8
+                     , ghc   >= 9.6   && < 9.8
diff --git a/src/HLint/Plugin/Settings.hs b/src/HLint/Plugin/Settings.hs
--- a/src/HLint/Plugin/Settings.hs
+++ b/src/HLint/Plugin/Settings.hs
@@ -20,18 +20,16 @@
     ) where
 
 import Control.Concurrent.MVar (MVar)
-import Data.IORef (IORef)
 import Data.Map (Map)
 import Language.Haskell.HLint (Classify, Hint, ParseFlags)
 
 import qualified Control.Concurrent.MVar as MVar
-import qualified Data.IORef as IORef
 import qualified Data.Map as Map
 import qualified Language.Haskell.HLint as HLint
 import qualified System.IO.Unsafe as Unsafe
 
-cache :: IORef (Map [String] (IO (ParseFlags, [Classify], Hint)))
-cache = Unsafe.unsafePerformIO (IORef.newIORef Map.empty)
+cache :: MVar (Map [String] (ParseFlags, [Classify], Hint))
+cache = Unsafe.unsafePerformIO (MVar.newMVar Map.empty)
 {-# NOINLINE cache #-}
 
 semaphore :: MVar ()
@@ -44,17 +42,14 @@
 argsSettings
     :: [String]
     -> IO (ParseFlags, [Classify], Hint)
-argsSettings key = do
-    io <- IORef.atomicModifyIORef' cache \m -> do
+argsSettings key =
+    MVar.modifyMVar cache \m -> do
         case Map.lookup key m of
-            Nothing      -> do
-                let io =
-                        Unsafe.unsafeInterleaveIO do
-                            MVar.withMVar semaphore \_ -> HLint.argsSettings key
-
-                (Map.insert key io m, io)
+            Nothing -> do
+                value <- Unsafe.unsafeInterleaveIO do
+                    MVar.withMVar semaphore \_ -> HLint.argsSettings key
 
-            Just io ->
-                (m, io)
+                pure (Map.insert key value m, value)
 
-    io
+            Just value ->
+                pure (m, value)