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73416ba
(Get the code!)
@Gérard Talbot No offense but it looks to me as if you're trying to convince everyone that there isn't any bug. I do think there's is something with this position:fixed
I wasn't comparing smoothscroll.
Here are the results again, with smoothscroll off:
FF2: between 3 and 5 seconds, redrawing maybe 4 or 5 times a second
FF3: between 13 and 15 seconds, redraw once a second
that's 4 to 5 times slower.
I've posted an attachment already a few weeks ago, cleaned up from all the images only but not css. I know I should have created a simple file with a fixed div and some text... I did read the 'howto' file a bug and do tests, etc...
But in my case it's a bit complex. So please bear with me and maybe advise me on how to proceed with this case.
In this case:
I have a png in the background, and a png in the fixed div, and a hole lot of tables, lot of stuff styled... All together it's slow. See results above.
If I get rid of the fixed div. It's back to normal, it's not slowed down. This tells me I'm in the correct bug, and I'm not posting in the wrong place.
BUT with the fixed div:
If I get rid of the png backgrounds and keep the fixed div, it's still slow but a lot better. And when I get rid of all the css styles, then it's back to a normal speed. Speed difference slightly visible.
I know it really sounds like it's something else in the code that slows it down, but I've spent a few hours removing rules one by one to see if there was a performance impact. And it became better, gradually; I couldn't see any difference each time I removed a rule. In the end there wasn't much an impact between 'not fixed' and 'fixed'.
Concludion:
- Clean of images and css, difference slightly visible.
- Alltogether, css, images, etc... Big difference between the version that has the fixed div and the one that hasn't.
Now I'm only speculating on how this is possible...
in FF2, a fixed div might have a 50% performance impact... So between the version that may take let's say, 100ms, it will take 150ms if there is a fixed div.
in FF3, there might be a 500% performance impact.
So on the simple test case like attachment #139911 where it takes 10ms to draw without fixed div, it would take 50ms, with a fixed div. 50ms is not slow. The few attachment indeed do not have any significant loss of performance.
But if the page takes 100 seconds to be drawn without fixed div because it's damn complex, it would take 500ms to redraw with fixed div.
So no I will not post a testcase like attachment #139911, because it doesn't represent what I get. But i don't really have any other ideas to post a test case whitout all the css and images. Anybody has any ideas on how to create a test case for this?