Why does Cygwin execute shell commands very slowly?

Question

Just tests a very simple command like:

while true; do bash -c \"echo hello\"; done

You will find how much slow the bash in Cygwin is. Does

Answer 1

Below are 3 possible causes which I encountered. Of course, other problems not mentioned can also cause slow shell commands in Cygwin.

• If you have the option "Automatically detect settings" in "LAN Settings", Windows will use the WPAD protocol to discover the local HTTP proxy. First it will send a DHCP "Inform" request with option 252, then it will try a DNS lookup on "wpad". These 2 operations can take a few seconds to time-out.

• If the shell accesses some paths like /cygdrive/... , a NetBIOS name query will be executed, which can also take some time to time out.

• If the shell accesses some paths like //mypath/... , a NetBIOS name query will be executed, which can also take some time to time out.

Solutions :

• Disable "Automatically detect settings" in "LAN Settings" in the Windows "Internet Options" control panel.

• Add the following entry in %SystemRoot%\system32\drivers\etc\hosts :

127.0.0.1 localhost cygdrive wpad

• Make sure to avoid double slashes at the beginning of all paths.