Frames per second for Javascript powered animations?

I'm working on a site that abuses Javascript pretty heavily for some constant animation effects; namely scrolling backgrounds. When running maximized in Firefox 3.6.13 at 1920x1080 it seems to lag, and sometimes ends up a bit skippy. When running at a smaller size though (resized to 50%-75%) it's very smooth.

I was just wondering if its possible to grab the number of discarded process开发者_运维知识库es, or loosely the FPS, that a given animation is running at. The animation is actually driven by window.setInterval() with a delay of 10 (1/100 of a second).

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http://forum.jquery.com/topic/why-jquery-uses-77-fps-by-default-in-animation

Credit to Google for the link :)