This is a simple framerate monitor for Firefox 4. The first version was hacked up in an hour or two. Expect many bugs!
To install, unpack this into the
packages/ directory in the Jetpack SDK. You
can get the Jetpack SDK here 1. Enter the Jetpack SDK, and use
source bin/activate. Then enter
packages/firefox-framerate-monitor, and use
cfx run to start Firefox.
If you'd like a pre-built binary, just download the XPI from the GitHub project page 2. Save the XPI file from the Downloads area (just click the big Downloads button) to your disk, and drag the file into Firefox to use it.
At the moment, profiling requires Mac OS X and Shark. You'll need to start Shark in remote mode to use the profiler. To switch to remote mode, choose "Programmatic (Remote)" from the Tools menu or press Cmd+Shift+R inside Shark. The most useful settings are WTF (windowed time facility) mode with 10000 samples, 20 usec sampling interval (not the default), and no time limit.