add warning about slow builds
diff --git a/WindowsCrossCompiling.md b/WindowsCrossCompiling.md
index 1fc6dbd..b90e0da 100644
--- a/WindowsCrossCompiling.md
+++ b/WindowsCrossCompiling.md
@@ -20,8 +20,13 @@
$ GOOS=windows GOARCH=386 go build -o hello.exe hello.go
```
-You can now run `hello.exe` on a Windows machine near you.
+You can now run `hello.exe` on a Windows machine near you.
+Note that the command above will silently rebuild most of standard library, and for this reason will be quite slow. To speed-up the process, you can install all the windows-amd64 standard packages on your system with
+
+```
+GOOS=windows GOARCH=amd64 go install
+```
## Older Go version (<1.5)
