diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,11 @@
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 0.16.1
+### Added
+- Cache mempool transactions.
+- Improve initial syncing performance.
+
 ## 0.16.0
 ### Added
 - Orphan transaction support.
diff --git a/haskoin-store.cabal b/haskoin-store.cabal
--- a/haskoin-store.cabal
+++ b/haskoin-store.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: a806db1bfb6b706e998c48d71994d5fe905b80350b267bcdfcb11398f97bee3e
+-- hash: 7bbe7347a0126be9bd8aec84b19b635f8acc5701fa8600737ea7d974fa5db2ea
 
 name:           haskoin-store
-version:        0.16.0
+version:        0.16.1
 synopsis:       Storage and index for Bitcoin and Bitcoin Cash
 description:    Store blocks, transactions, and balances for Bitcoin or Bitcoin Cash, and make that information via REST API.
 category:       Bitcoin, Finance, Network
diff --git a/src/Network/Haskoin/Store/Data/Cached.hs b/src/Network/Haskoin/Store/Data/Cached.hs
--- a/src/Network/Haskoin/Store/Data/Cached.hs
+++ b/src/Network/Haskoin/Store/Data/Cached.hs
@@ -32,6 +32,7 @@
 newLayeredDB blocks (Just cache) = do
     bulkCopy opts db cdb BalKeyS
     bulkCopy opts db cdb UnspentKeyB
+    bulkCopy opts db cdb MemKeyS
     return LayeredDB {layeredDB = blocks, layeredCache = Just cache}
   where
     BlockDB {blockDBopts = opts, blockDB = db} = blocks
@@ -81,7 +82,8 @@
     => Maybe UnixTime
     -> LayeredDB
     -> ConduitT () (UnixTime, TxHash) m ()
-getMempoolC mpu LayeredDB {layeredDB = db} = getMempoolDB mpu db
+getMempoolC mpu LayeredDB {layeredCache = Just db} = getMempoolDB mpu db
+getMempoolC mpu LayeredDB {layeredDB = db}         = getMempoolDB mpu db
 
 getOrphansC ::
        (MonadUnliftIO m, MonadResource m)
diff --git a/src/Network/Haskoin/Store/Data/ImportDB.hs b/src/Network/Haskoin/Store/Data/ImportDB.hs
--- a/src/Network/Haskoin/Store/Data/ImportDB.hs
+++ b/src/Network/Haskoin/Store/Data/ImportDB.hs
@@ -77,8 +77,7 @@
 
 cacheMapOps :: BlockMem -> [BatchOp]
 cacheMapOps db =
-    balOps (hBalance db) <>
-    unspentOps (hUnspent db)
+    balOps (hBalance db) <> mempoolOps (hMempool db) <> unspentOps (hUnspent db)
 
 bestBlockOp :: Maybe BlockHash -> [BatchOp]
 bestBlockOp Nothing  = []
@@ -315,6 +314,29 @@
 deleteUnspentI p ImportDB {importHashMap = hm} =
     withBlockMem hm $ deleteUnspent p
 
+getMempoolI ::
+       MonadIO m
+    => Maybe UnixTime
+    -> ImportDB
+    -> ConduitT () (UnixTime, TxHash) m ()
+getMempoolI mpu ImportDB {importHashMap = hm, importLayeredDB = db} = do
+    h <- hMempool <$> readTVarIO hm
+    let hmap =
+            M.fromList . filter tfilter $
+            concatMap
+                (\(u, l) -> map (\(t, b) -> ((u, t), b)) (M.toList l))
+                (M.toList h)
+    dmap <-
+        fmap M.fromList . liftIO . runResourceT . withLayeredDB db . runConduit $
+        getMempool mpu .| mapC (, True) .| sinkList
+    let rmap = M.filter id (M.union hmap dmap)
+    yieldMany $ sortBy (flip compare) (M.keys rmap)
+  where
+    tfilter =
+        case mpu of
+            Just x -> (<= x) . fst . fst
+            Nothing -> const True
+
 instance MonadIO m => StoreRead (ReaderT ImportDB m) where
     isInitialized = R.ask >>= isInitializedI
     getBestBlock = R.ask >>= getBestBlockI
@@ -346,3 +368,11 @@
     insertUnspent u = R.ask >>= insertUnspentI u
     deleteUnspent p = R.ask >>= deleteUnspentI p
     setBalance b = R.ask >>= setBalanceI b
+
+instance MonadIO m => StoreStream (ReaderT ImportDB m) where
+    getMempool m = R.ask >>= getMempoolI m
+    getOrphans = undefined
+    getAddressUnspents a m = undefined
+    getAddressTxs a m = undefined
+    getAddressBalances = undefined
+    getUnspents = undefined
diff --git a/src/Network/Haskoin/Store/Logic.hs b/src/Network/Haskoin/Store/Logic.hs
--- a/src/Network/Haskoin/Store/Logic.hs
+++ b/src/Network/Haskoin/Store/Logic.hs
@@ -54,6 +54,7 @@
 initDB ::
        ( StoreRead m
        , StoreWrite m
+       , StoreStream m
        , MonadLogger m
        , MonadError ImportException m
        )
@@ -75,10 +76,7 @@
             importBlock net (genesisBlock net) (genesisNode net)
             setInit
 
-getOldOrphans ::
-       (StoreStream m, MonadResource m)
-    => UnixTime
-    -> ConduitT () TxHash m ()
+getOldOrphans :: (Monad m, StoreStream m) => UnixTime -> ConduitT () TxHash m ()
 getOldOrphans now =
     getOrphans .| filterC ((< now - 600) . fst) .| mapC (txHash . snd)
 
@@ -222,6 +220,7 @@
 
 importBlock ::
        ( StoreRead m
+       , StoreStream m
        , StoreWrite m
        , MonadLogger m
        , MonadError ImportException m
@@ -231,59 +230,66 @@
     -> BlockNode
     -> m ()
 importBlock net b n = do
-        getBestBlock >>= \case
-            Nothing
-                | isGenesis n -> do
-                    $(logInfoS) "BlockLogic" $
-                        "Importing genesis block: " <>
-                        blockHashToHex (headerHash (nodeHeader n))
-                    return ()
-                | otherwise -> do
-                    $(logErrorS) "BlockLogic" $
-                        "Importing non-genesis block when best block unknown: " <>
-                        blockHashToHex (headerHash (blockHeader b))
-                    throwError BestBlockUnknown
-            Just h
-                | prevBlock (blockHeader b) == h -> return ()
-                | otherwise -> do
-                    $(logErrorS) "BlockLogic" $
-                        "Block " <> blockHashToHex (headerHash (blockHeader b)) <>
-                        " does not build on current best " <>
-                        blockHashToHex h
-                    throwError
-                        (PrevBlockNotBest
-                             (blockHashToHex (prevBlock (nodeHeader n))))
-        insertBlock
-            BlockData
-                { blockDataHeight = nodeHeight n
-                , blockDataMainChain = True
-                , blockDataWork = nodeWork n
-                , blockDataHeader = nodeHeader n
-                , blockDataSize = fromIntegral (B.length (encode b))
-                , blockDataTxs = map txHash (blockTxns b)
-                , blockDataWeight = fromIntegral w
-                , blockDataSubsidy = subsidy (nodeHeight n)
-                , blockDataFees = cb_out_val - subsidy (nodeHeight n)
-                , blockDataOutputs = ts_out_val
-                }
-        insertAtHeight (headerHash (nodeHeader n)) (nodeHeight n)
-        setBest (headerHash (nodeHeader n))
-        $(logDebugS) "Block" $ "Importing or confirming block transactions..."
-        mapM_ (uncurry import_or_confirm) (sortTxs (blockTxns b))
-        $(logDebugS) "Block" $
-            "Done importing transactions for block " <>
-            blockHashToHex (headerHash (nodeHeader n))
+    mp <-
+        runConduit $
+        getMempool Nothing .| mapC snd .| filterC (`elem` bths) .| sinkList
+    getBestBlock >>= \case
+        Nothing
+            | isGenesis n -> do
+                $(logInfoS) "BlockLogic" $
+                    "Importing genesis block: " <>
+                    blockHashToHex (headerHash (nodeHeader n))
+                return ()
+            | otherwise -> do
+                $(logErrorS) "BlockLogic" $
+                    "Importing non-genesis block when best block unknown: " <>
+                    blockHashToHex (headerHash (blockHeader b))
+                throwError BestBlockUnknown
+        Just h
+            | prevBlock (blockHeader b) == h -> return ()
+            | otherwise -> do
+                $(logErrorS) "BlockLogic" $
+                    "Block " <> blockHashToHex (headerHash (blockHeader b)) <>
+                    " does not build on current best " <>
+                    blockHashToHex h
+                throwError
+                    (PrevBlockNotBest
+                         (blockHashToHex (prevBlock (nodeHeader n))))
+    insertBlock
+        BlockData
+            { blockDataHeight = nodeHeight n
+            , blockDataMainChain = True
+            , blockDataWork = nodeWork n
+            , blockDataHeader = nodeHeader n
+            , blockDataSize = fromIntegral (B.length (encode b))
+            , blockDataTxs = map txHash (blockTxns b)
+            , blockDataWeight = fromIntegral w
+            , blockDataSubsidy = subsidy (nodeHeight n)
+            , blockDataFees = cb_out_val - subsidy (nodeHeight n)
+            , blockDataOutputs = ts_out_val
+            }
+    insertAtHeight (headerHash (nodeHeader n)) (nodeHeight n)
+    setBest (headerHash (nodeHeader n))
+    $(logDebugS) "Block" $ "Importing or confirming block transactions..."
+    mapM_ (uncurry (import_or_confirm mp)) (sortTxs (blockTxns b))
+    $(logDebugS) "Block" $
+        "Done importing transactions for block " <>
+        blockHashToHex (headerHash (nodeHeader n))
   where
-    import_or_confirm x tx =
-        getTxData (txHash tx) >>= \case
-            Just t
-                | x > 0 && not (txDataDeleted t) -> do confirmTx net t (br x) tx
-            _ -> do
-                importTx
-                    net
-                    (br x)
-                    (fromIntegral (blockTimestamp (nodeHeader n)))
-                    tx
+    bths = map txHash (blockTxns b)
+    import_or_confirm mp x tx =
+        if txHash tx `elem` mp
+            then getTxData (txHash tx) >>= \case
+                     Just td -> confirmTx net td (br x) tx
+                     Nothing -> do
+                         $(logErrorS) "Block" $
+                             "Cannot get data for transaction in mempool"
+                         throwError $ TxNotFound (txHashToHex (txHash tx))
+            else importTx
+                     net
+                     (br x)
+                     (fromIntegral (blockTimestamp (nodeHeader n)))
+                     tx
     subsidy = computeSubsidy net
     cb_out_val = sum (map outValue (txOut (head (blockTxns b))))
     ts_out_val = sum (map (sum . map outValue . txOut) (tail (blockTxns b)))