Note: Speed of opening new windows in tabs is not affected, at least in Firefox. Disable opening "new windows in a new tab instead," or use the "Pop-up" Window test.

Needless to say, you need JavaScript enabled. :-)

Download Browser Launch Benchmark — This page, plus a Windows launcher script to time full browser launching time (not necessary). If your browser isn't a Forced Program, just use "Run Sandboxed" on the Run Browser.js file.