Firefox 3.6 performance issues & hidden boost

Ok this is slightly mysterious. I am working on a site where a bunch transparent pngs overlay eachother and move at slightly different speeds. In firefox 3.6 this is kinda choppy.

After some research yesterday I found that by putting the images as background css I would get some开发者_Python百科 performance boost. And magically it did. This morning when I turned on my computer, all this performance was gone. So I searched the internet again (opening some tabs) and bam! the performance was back, without changing any code.

After testing this, everytime I open 3 or 4 new tabs in a fresh firefox, the performance comes back (choppiness is totally gone). Now I guess there is some mechanism in firefox 3.6 that tells it to use more resources or something... or some hardware rendering. And I wonder if there would a way to utilize this magic when i just have one tab opened? Because it would be silly to ask the user to open 3 tabs to get optimal performance.

It might be your video card or cpu and not firefox that is doing the magic. Especially if it's a laptop with lots of power saving functions.

Repeat your test but instead of opening 3 extra tabs, start an hd-video or other resource intensve operation in another program.