diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,1 +1,4 @@
+0.1.1
+---
 
+* Add `use-text-show` flag to optionally use more efficient `TextShow` instances
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
 # http-api-data
 
+[![Hackage package](http://img.shields.io/hackage/v/http-api-data.svg)](http://hackage.haskell.org/package/http-api-data)
 [![Build Status](https://secure.travis-ci.org/fizruk/http-api-data.png?branch=master)](http://travis-ci.org/fizruk/http-api-data)
 
 This package defines typeclasses used for converting Haskell data types to and from HTTP API data.
diff --git a/Web/HttpApiData/Internal.hs b/Web/HttpApiData/Internal.hs
--- a/Web/HttpApiData/Internal.hs
+++ b/Web/HttpApiData/Internal.hs
@@ -34,6 +34,10 @@
 import Text.Read (readMaybe)
 import Text.ParserCombinators.ReadP (readP_to_S)
 
+#if USE_TEXT_SHOW
+import TextShow (TextShow, showt)
+#endif
+
 -- | Convert value to HTTP API data.
 class ToHttpApiData a where
   {-# MINIMAL toUrlPiece | toQueryParam #-}
@@ -96,6 +100,27 @@
     Nothing  -> defaultParseError input
     Just val -> Right val
 
+#if USE_TEXT_SHOW
+-- | Convert to URL piece using @'TextShow'@ instance.
+-- The result is always lower cased.
+--
+-- >>> showTextData True
+-- "true"
+--
+-- This can be used as a default implementation for enumeration types:
+--
+-- @
+-- data MyData = Foo | Bar | Baz deriving (Generic)
+-- 
+-- instance TextShow MyData where
+--   showt = genericShowt
+--
+-- instance ToHttpApiData MyData where
+--   toUrlPiece = showTextData
+-- @
+showTextData :: TextShow a => a -> Text
+showTextData = T.toLower . showt
+#else
 -- | Convert to URL piece using @'Show'@ instance.
 -- The result is always lower cased.
 --
@@ -109,8 +134,13 @@
 -- >>> toUrlPiece Foo
 -- "foo"
 showTextData :: Show a => a -> Text
-showTextData = T.toLower . T.pack . show
+showTextData = T.toLower . showt
 
+-- | Like @'show'@, but returns @'Text'@.
+showt :: Show a => a -> Text
+showt = T.pack . show
+#endif
+
 -- | Parse given text case insensitive and return the rest of the input.
 --
 -- >>> parseUrlPieceWithPrefix "Just " "just 10" :: Either Text Int
@@ -131,6 +161,27 @@
   where
     (prefix, rest) = T.splitAt (T.length pattern) input
 
+#if USE_TEXT_SHOW
+-- | Parse values case insensitively based on @'TextShow'@ instance.
+--
+-- >>> parseBoundedCaseInsensitiveTextData "true" :: Either Text Bool
+-- Right True
+-- >>> parseBoundedCaseInsensitiveTextData "FALSE" :: Either Text Bool
+-- Right False
+--
+-- This can be used as a default implementation for enumeration types:
+--
+-- @
+-- data MyData = Foo | Bar | Baz deriving (Show, Bounded, Enum, Generic)
+--
+-- instance TextShow MyData where
+--   showt = genericShowt
+--
+-- instance FromHttpApiData MyData where
+--   parseUrlPiece = parseBoundedCaseInsensitiveTextData
+-- @
+parseBoundedCaseInsensitiveTextData :: forall a. (TextShow a, Bounded a, Enum a) => Text -> Either Text a
+#else
 -- | Parse values case insensitively based on @'Show'@ instance.
 --
 -- >>> parseBoundedCaseInsensitiveTextData "true" :: Either Text Bool
@@ -145,6 +196,7 @@
 -- >>> parseUrlPiece "foo" :: Either Text MyData
 -- Right Foo
 parseBoundedCaseInsensitiveTextData :: forall a. (Show a, Bounded a, Enum a) => Text -> Either Text a
+#endif
 parseBoundedCaseInsensitiveTextData = parseMaybeTextData (flip lookup values . T.toLower)
   where
     values = map (showTextData &&& id) [minBound..maxBound :: a]
@@ -201,23 +253,25 @@
 
 instance ToHttpApiData Bool     where toUrlPiece = showTextData
 instance ToHttpApiData Ordering where toUrlPiece = showTextData
-instance ToHttpApiData Double   where toUrlPiece = showTextData
-instance ToHttpApiData Float    where toUrlPiece = showTextData
-instance ToHttpApiData Int      where toUrlPiece = showTextData
-instance ToHttpApiData Int8     where toUrlPiece = showTextData
-instance ToHttpApiData Int16    where toUrlPiece = showTextData
-instance ToHttpApiData Int32    where toUrlPiece = showTextData
-instance ToHttpApiData Int64    where toUrlPiece = showTextData
-instance ToHttpApiData Integer  where toUrlPiece = showTextData
-instance ToHttpApiData Word     where toUrlPiece = showTextData
-instance ToHttpApiData Word8    where toUrlPiece = showTextData
-instance ToHttpApiData Word16   where toUrlPiece = showTextData
-instance ToHttpApiData Word32   where toUrlPiece = showTextData
-instance ToHttpApiData Word64   where toUrlPiece = showTextData
+
+instance ToHttpApiData Double   where toUrlPiece = showt
+instance ToHttpApiData Float    where toUrlPiece = showt
+instance ToHttpApiData Int      where toUrlPiece = showt
+instance ToHttpApiData Int8     where toUrlPiece = showt
+instance ToHttpApiData Int16    where toUrlPiece = showt
+instance ToHttpApiData Int32    where toUrlPiece = showt
+instance ToHttpApiData Int64    where toUrlPiece = showt
+instance ToHttpApiData Integer  where toUrlPiece = showt
+instance ToHttpApiData Word     where toUrlPiece = showt
+instance ToHttpApiData Word8    where toUrlPiece = showt
+instance ToHttpApiData Word16   where toUrlPiece = showt
+instance ToHttpApiData Word32   where toUrlPiece = showt
+instance ToHttpApiData Word64   where toUrlPiece = showt
+instance ToHttpApiData Day      where toUrlPiece = T.pack . show
+
 instance ToHttpApiData String   where toUrlPiece = T.pack
 instance ToHttpApiData Text     where toUrlPiece = id
 instance ToHttpApiData L.Text   where toUrlPiece = L.toStrict
-instance ToHttpApiData Day      where toUrlPiece = showTextData
 
 instance ToHttpApiData All where toUrlPiece = toUrlPiece . getAll
 instance ToHttpApiData Any where toUrlPiece = toUrlPiece . getAny
diff --git a/http-api-data.cabal b/http-api-data.cabal
--- a/http-api-data.cabal
+++ b/http-api-data.cabal
@@ -1,5 +1,5 @@
 name:            http-api-data
-version:         0.1.0
+version:         0.1.1
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -16,11 +16,18 @@
   CHANGELOG.md
   README.md
 
+flag use-text-show
+  description: Use @text-show@ library for efficient @'ToHttpApiData'@ implementations.
+  default: False
+
 library
     build-depends:   base             >= 4       && < 5
                    , text             >= 0.5
                    , bytestring
                    , time
+    if flag(use-text-show)
+      cpp-options: -DUSE_TEXT_SHOW
+      build-depends: text-show        >= 2
     exposed-modules:
       Web.HttpApiData
       Web.HttpApiData.Internal