Firefox and Chrome are known to be slow on localhost when IP6 is enabled. In previous versions of Windows, the simplest fix is to comment out this line from the hosts file, as explained in the answer to this question.
::1 localhost
However, as noted in this question, in Windows 7 this line is already commented out:
# localhost name resolution is handled within DNS itself.
# 127.0.0.1 localhost
# ::1 localhost
Is there an alternative way to disable the ::1 localhost
reference in Windows 7?
Turns out if you uncomment the 127.0.0.1 line in the hosts file, Chrome goes back to its snappy self on localhost URLs.
# localhost name resolution is handled within DNS itself.
127.0.0.1 localhost
The hosts file is typically at C:\WINDOWS\system32\drivers\etc\hosts
. To edit it in Win7, you'll need to run Notepad as administrator.