diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,16 @@
+filepath-bytestring (1.4.2.1.8) unstable; urgency=medium
+
+  * Faster implementations of encodeFilePath and decodeFilePath.
+    They are approximately 2x and 3x as fast, respectively.
+  * encodeFilePath and decodeFilePath used to truncate at the first
+    NUL. The new implementations do not do this. Since unix filepaths
+    cannot contain NUL, this behavior change is can't cause any problems,
+    unless the functions are used for values that are not actually
+    valid filepaths.
+  * Support cabal bench to benchmark the library.
+
+ -- Joey Hess <id@joeyh.name>  Wed, 11 Aug 2021 12:17:15 -0400
+
 filepath-bytestring (1.4.2.1.7) unstable; urgency=medium
 
   * Relax QuickCheck bounds to allow 2.14.
diff --git a/System/FilePath/Internal.hs b/System/FilePath/Internal.hs
--- a/System/FilePath/Internal.hs
+++ b/System/FilePath/Internal.hs
@@ -136,6 +136,7 @@
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as B
 import qualified Data.ByteString.Char8 as B8
+import Data.ByteString.Unsafe (unsafePackMallocCStringLen)
 import Data.Char(ord, chr, toUpper, toLower, isAsciiLower, isAsciiUpper)
 import Data.Maybe(isJust)
 import Data.Word(Word8)
@@ -174,13 +175,9 @@
 #ifdef mingw32_HOST_OS
 encodeFilePath = UTF8.fromString
 #else
-encodeFilePath = B.pack . map (fromIntegral . fromEnum) . encodeFilePath'
-
-{-# NOINLINE encodeFilePath' #-}
-encodeFilePath' :: FilePath -> String
-encodeFilePath' f = unsafePerformIO $ do
+encodeFilePath f = unsafePerformIO $ do
 	enc <- Encoding.getFileSystemEncoding
-	GHC.withCString enc f (GHC.peekCString Encoding.char8)
+	GHC.newCStringLen enc f >>= unsafePackMallocCStringLen
 #endif
 
 -- | Convert from RawFilePath to FilePath
@@ -193,15 +190,11 @@
 #ifdef mingw32_HOST_OS
 decodeFilePath = UTF8.toString
 #else
-decodeFilePath = decodeFilePath' . map (toEnum . fromIntegral) . B.unpack
-
-{-# NOINLINE decodeFilePath' #-}
-decodeFilePath' :: String -> FilePath
-decodeFilePath' s = unsafePerformIO $ do
+{-# NOINLINE decodeFilePath #-}
+decodeFilePath f = unsafePerformIO $ do
 	enc <- Encoding.getFileSystemEncoding
-	GHC.withCString Encoding.char8 s (GHC.peekCString enc)
+	B.useAsCStringLen f (GHC.peekCStringLen enc)
 #endif
-
 
 ---------------------------------------------------------------------
 -- Platform Abstraction Methods (private)
diff --git a/benchmark/benchmark.hs b/benchmark/benchmark.hs
new file mode 100644
--- /dev/null
+++ b/benchmark/benchmark.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import qualified System.FilePath as FilePath
+import qualified System.FilePath.ByteString as RawFilePath
+import Criterion.Main
+
+main :: IO ()
+main = defaultMain
+	[ bgroup "combine"
+		[ bench "FilePath" $ nf (FilePath.combine "foo") "bar"
+		, bench "RawFilePath" $ nf (RawFilePath.combine "foo") "bar"
+		]
+	, bgroup "dropTrailingPathSeparator"
+		[ bench "FilePath" $ nf FilePath.dropTrailingPathSeparator "foo/"
+		, bench "RawFilePath" $ nf RawFilePath.dropTrailingPathSeparator "foo/"
+		]
+	, bgroup "FilePath conversion"
+		[ bench "encode" $ nf RawFilePath.encodeFilePath "foobar.baz"
+		, bench "decode" $ nf RawFilePath.decodeFilePath "foobar.baz"
+		]
+	]
diff --git a/filepath-bytestring.cabal b/filepath-bytestring.cabal
--- a/filepath-bytestring.cabal
+++ b/filepath-bytestring.cabal
@@ -1,13 +1,13 @@
 cabal-version: 1.18
 name:           filepath-bytestring
-version:        1.4.2.1.7
+version:        1.4.2.1.8
 -- NOTE: Don't forget to update CHANGELOG and the filepath dependency below
 license:        BSD3
 license-file:   LICENSE
 author:         Neil Mitchell <ndmitchell@gmail.com>
 maintainer:     Joey Hess <id@joeyh.name>
 copyright:      Neil Mitchell 2005-2019
-                Joey Hess 2019
+                Joey Hess 2019-2021
 category:       System
 build-type:     Simple
 synopsis:       Library for manipulating RawFilePaths in a cross platform way.
@@ -75,4 +75,17 @@
         QuickCheck >= 2.7 && < 2.15,
 	-- Versions of filepath that are equvilant to this
 	-- library, for quickcheck equivilance tests.
+        filepath >= 1.4.2 && <= 1.4.2.1
+
+benchmark filepath-bench
+    type: exitcode-stdio-1.0
+    default-language: Haskell2010
+    main-is: benchmark.hs
+    ghc-options: -O2 -Wall -fno-warn-tabs
+    hs-source-dirs: benchmark
+    build-depends: 
+        base,
+        criterion,
+        filepath-bytestring,
+	-- Version of filepath to benchmark against
         filepath >= 1.4.2 && <= 1.4.2.1