Comment 89 for bug 217580

> asac, I've just reproduced the slow scrolling with fixed position
> elements in gmail, with 3.6 from that ppa

That is bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=427431

So iirc, we had a few performance issues in 1.9/3.0:
 1. border painting slow - https://bugzilla.mozilla.org/show_bug.cgi?id=424423 (fixed in ffox 3.5 + trunk)
 2. dashed and dotted borders slow - https://bugzilla.mozilla.org/show_bug.cgi?id=422330 (partially fixed in 3.5 + trunk because of 1.)
 3. scrolling of non-fixed elements sluggish when fixed elements are available - https://bugzilla.mozilla.org/show_bug.cgi?id=382392 (fixed in 3.0 final)
 4. absolute positioned elements still slow after 3. - https://bugzilla.mozilla.org/show_bug.cgi?id=427431