diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # dir-traverse
 
+## 0.2.2.3
+
+  * Performance improvements with `unsafeInterleaveIO`
+
 ## 0.2.2.2
 
   * Bugfix
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -3,3 +3,5 @@
 Get all descendants of a directory. It should have similar performance to
 [dirstream](http://hackage.haskell.org/package/dirstream), with fewer
 dependencies.
+
+This streams in memory, like `dirstream`.
diff --git a/dir-traverse.cabal b/dir-traverse.cabal
--- a/dir-traverse.cabal
+++ b/dir-traverse.cabal
@@ -1,6 +1,6 @@
 cabal-version:   1.18
 name:            dir-traverse
-version:         0.2.2.2
+version:         0.2.2.3
 license:         BSD3
 license-file:    LICENSE
 copyright:       Copyright: (c) 2019 Vanessa McHale
@@ -51,6 +51,24 @@
         pipes-safe -any,
         system-filepath -any,
         directory -any
+
+    if impl(ghc >=8.0)
+        ghc-options:
+            -Wincomplete-uni-patterns -Wincomplete-record-updates
+            -Wredundant-constraints -Widentities
+
+    if impl(ghc >=8.4)
+        ghc-options: -Wmissing-export-lists
+
+benchmark mem
+    type:             exitcode-stdio-1.0
+    main-is:          Mem.hs
+    hs-source-dirs:   mem
+    default-language: Haskell2010
+    ghc-options:      -Wall
+    build-depends:
+        base -any,
+        dir-traverse -any
 
     if impl(ghc >=8.0)
         ghc-options:
diff --git a/mem/Mem.hs b/mem/Mem.hs
new file mode 100644
--- /dev/null
+++ b/mem/Mem.hs
@@ -0,0 +1,10 @@
+module Main ( main ) where
+
+import           System.Directory.Recursive (getDirRecursive)
+import           System.Environment         (getArgs)
+
+main :: IO ()
+main = force $ getDirRecursive . head =<< getArgs
+
+force :: IO [FilePath] -> IO ()
+force x = (\fps -> last fps `seq` mempty) =<< x
diff --git a/src/System/Directory/Recursive.hs b/src/System/Directory/Recursive.hs
--- a/src/System/Directory/Recursive.hs
+++ b/src/System/Directory/Recursive.hs
@@ -9,6 +9,7 @@
 import           Data.Traversable    (traverse)
 import           System.Directory    (doesDirectoryExist, listDirectory)
 import           System.FilePath     ((</>))
+import           System.IO.Unsafe    (unsafeInterleaveIO)
 
 
 -- | @since 0.2.1.0
@@ -30,7 +31,7 @@
     case dirs of
         [] -> pure all''
         ds -> do
-            next <- foldMapA (getDirFiltered p) ds
+            next <- unsafeInterleaveIO $ foldMapA (getDirFiltered p) ds
             pure $ all'' ++ next
 
     where mkRel = (fp </>)