diff --git a/Network/Wai/Handler/Warp.hs b/Network/Wai/Handler/Warp.hs
--- a/Network/Wai/Handler/Warp.hs
+++ b/Network/Wai/Handler/Warp.hs
@@ -32,6 +32,7 @@
   , settingsIntercept
   , settingsManager
   , settingsFdCacheDuration
+  , settingsResourceTPerRequest
     -- ** Data types
   , HostPreference (..)
     -- * Connection
diff --git a/Network/Wai/Handler/Warp/Conduit.hs b/Network/Wai/Handler/Warp/Conduit.hs
--- a/Network/Wai/Handler/Warp/Conduit.hs
+++ b/Network/Wai/Handler/Warp/Conduit.hs
@@ -6,7 +6,9 @@
 import Control.Monad.IO.Class (MonadIO, liftIO)
 import Control.Monad.Trans.Class (lift)
 import Data.ByteString (ByteString)
+import Data.ByteString.Lazy.Char8 (pack)
 import qualified Data.ByteString as S
+import qualified Data.ByteString.Lazy as L
 import Data.Conduit
 import qualified Data.Conduit.Binary as CB
 import Data.Conduit.Internal (ResumableSource (..))
@@ -95,7 +97,9 @@
     go src NeedLenNewline = go' src (CB.take 2 >>)
     go src (HaveLen 0) = do
         -- Drop the final CRLF
-        (src', ()) <- lift $ src $$++ CB.drop 2
+        (src', ()) <- lift $ src $$++ do
+            crlf <- CB.take 2
+            unless (crlf == pack "\r\n") $ leftover $ S.concat $ L.toChunks crlf
         liftIO $ I.writeIORef ipair (src', HaveLen 0)
     go src (HaveLen len) = do
         (src', mbs) <- lift $ src $$++ CL.head
diff --git a/Network/Wai/Handler/Warp/Run.hs b/Network/Wai/Handler/Warp/Run.hs
--- a/Network/Wai/Handler/Warp/Run.hs
+++ b/Network/Wai/Handler/Warp/Run.hs
@@ -8,6 +8,7 @@
 import Control.Exception
 import Control.Monad (forever, when, unless, void)
 import Control.Monad.IO.Class (MonadIO, liftIO)
+import Control.Monad.Trans.Class (lift)
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as S
 import Data.Conduit
@@ -40,7 +41,10 @@
 #if WINDOWS
 import qualified Control.Concurrent.MVar as MV
 import Network.Socket (withSocketsDo)
-#else
+#endif
+
+#if SENDFILEFD
+import Control.Applicative
 import qualified Network.Wai.Handler.Warp.FdCache as F
 #endif
 
@@ -67,13 +71,15 @@
     }
 
 sendFile :: Socket -> FilePath -> Integer -> Integer -> IO () -> [ByteString] -> Cleaner -> IO ()
-#if WINDOWS
+#if SENDFILEFD
+sendFile s path off len act hdr cleaner = case fdCacher cleaner of
+    Nothing  -> sendfileWithHeader s path (PartOfFile off len) act hdr
+    Just fdc -> do
+        (fd, fresher) <- F.getFd fdc path
+        sendfileFdWithHeader s fd (PartOfFile off len) (act>>fresher) hdr
+#else
 sendFile s path off len act hdr _ =
     sendfileWithHeader s path (PartOfFile off len) act hdr
-#else
-sendFile s path off len act hdr cleaner = do
-    (fd, fresher) <- F.getFd (fdCacher cleaner) path
-    sendfileFdWithHeader s fd (PartOfFile off len) (act>>fresher) hdr
 #endif
 
 #if __GLASGOW_HASKELL__ < 702
@@ -125,18 +131,21 @@
 runSettingsConnection set getConn app = do
     tm <- maybe (T.initialize $ settingsTimeout set * 1000000) return
         $ settingsManager set
-#if !WINDOWS
-    fc <- F.initialize (settingsFdCacheDuration set * 1000000)
+#if SENDFILEFD
+    let duration = settingsFdCacheDuration set
+    fc <- case duration of
+        0 -> return Nothing
+        _ -> Just <$> F.initialize (duration * 1000000)
 #endif
     mask $ \restore -> forever $ do
         allowInterrupt
         (conn, addr) <- getConnLoop
         void . forkIO $ do
             th <- T.registerKillThread tm
-#if WINDOWS
-            let cleaner = Cleaner th
-#else
+#if SENDFILEFD
             let cleaner = Cleaner th fc
+#else
+            let cleaner = Cleaner th
 #endif
             let serve = do
                     onOpen
@@ -163,6 +172,9 @@
 serveConnection settings cleaner port app conn remoteHost' =
     runResourceT serveConnection'
   where
+    innerRunResourceT
+        | settingsResourceTPerRequest settings = lift . runResourceT
+        | otherwise = id
     th = threadHandle cleaner
 
     serveConnection' :: ResourceT IO ()
@@ -174,10 +186,11 @@
             Nothing -> do
                 -- Let the application run for as long as it wants
                 liftIO $ T.pause th
-                res <- app env
+                keepAlive <- innerRunResourceT $ do
+                    res <- app env
 
-                liftIO $ T.resume th
-                keepAlive <- sendResponse cleaner env conn res
+                    liftIO $ T.resume th
+                    sendResponse cleaner env conn res
 
                 -- flush the rest of the request body
                 requestBody env $$ CL.sinkNull
diff --git a/Network/Wai/Handler/Warp/Settings.hs b/Network/Wai/Handler/Warp/Settings.hs
--- a/Network/Wai/Handler/Warp/Settings.hs
+++ b/Network/Wai/Handler/Warp/Settings.hs
@@ -25,7 +25,12 @@
     , settingsTimeout :: Int -- ^ Timeout value in seconds. Default value: 30
     , settingsIntercept :: Request -> Maybe (Source (ResourceT IO) S.ByteString -> Connection -> ResourceT IO ())
     , settingsManager :: Maybe Manager -- ^ Use an existing timeout manager instead of spawning a new one. If used, 'settingsTimeout' is ignored. Default is 'Nothing'
-    , settingsFdCacheDuration :: Int -- ^ Cache duratoin time of file descriptors in seconds. Default value: 10
+    , settingsFdCacheDuration :: Int -- ^ Cache duratoin time of file descriptors in seconds. 0 means that the cache mechanism is not used. Default value: 10
+    , settingsResourceTPerRequest :: Bool
+      -- ^ If @True@, each request\/response pair will run in a separate
+      -- @ResourceT@. This provides more intuitive behavior for dynamic code,
+      -- but can hinder performance in high-throughput cases. File servers can
+      -- safely set to @False@ for increased performance. Default is @True@.
     }
 
 -- | The default settings for the Warp server. See the individual settings for
@@ -46,6 +51,7 @@
     , settingsIntercept = const Nothing
     , settingsManager = Nothing
     , settingsFdCacheDuration = 10
+    , settingsResourceTPerRequest = True
     }
   where
     go :: InvalidRequest -> IO ()
diff --git a/Network/Wai/Handler/Warp/Types.hs b/Network/Wai/Handler/Warp/Types.hs
--- a/Network/Wai/Handler/Warp/Types.hs
+++ b/Network/Wai/Handler/Warp/Types.hs
@@ -11,7 +11,7 @@
 import Network.HTTP.Types.Header
 import qualified Paths_warp
 import qualified Network.Wai.Handler.Warp.Timeout as T
-#if !WINDOWS
+#if SENDFILEFD
 import qualified Network.Wai.Handler.Warp.FdCache as F
 #endif
 
@@ -78,11 +78,11 @@
 
 ----------------------------------------------------------------
 
-#if WINDOWS
-newtype Cleaner = Cleaner { threadHandle :: T.Handle }
-#else
+#if SENDFILEFD
 data Cleaner = Cleaner {
     threadHandle :: T.Handle
-  , fdCacher :: F.MutableFdCache
+  , fdCacher :: Maybe F.MutableFdCache
   }
+#else
+newtype Cleaner = Cleaner { threadHandle :: T.Handle }
 #endif
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             1.3.2
+Version:             1.3.3
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE
@@ -48,13 +48,14 @@
                      Network.Wai.Handler.Warp.Types
                      Paths_warp
   Ghc-Options:       -Wall
-  if os(windows)
-      Cpp-options:   -DWINDOWS
-  else
+  if os(linux) || os(freebsd) || os(darwin)
+      Cpp-Options:   -DSENDFILEFD
       Build-Depends: unix
                    , hashable
       Other-modules: Network.Wai.Handler.Warp.FdCache
                      Network.Wai.Handler.Warp.MultiMap
+  if os(windows)
+      Cpp-Options:   -DWINDOWS
 
 Test-Suite spec
     Main-Is:         Spec.hs
@@ -81,11 +82,12 @@
                    , HUnit
                    , QuickCheck
                    , hspec                    == 1.3.*
-  if os(windows)
-      Cpp-options:   -DWINDOWS
-  else
+  if os(linux) || os(freebsd) || os(darwin)
+      Cpp-Options:   -DSENDFILEFD
       Build-Depends: unix
                    , hashable
+  if os(windows)
+      Cpp-Options:   -DWINDOWS
 
 Source-Repository head
   Type:     git