Comment 37 for bug 125970

Created an attachment (id=139911)
test demonstrating affect of multiple fixed elements

while working on a page design, i noticed that the number of position:fixed
elements affected the scroll speed, which led me to look up this bug. at first
it seemed like any number more than one would cause a serious slow down, but
after creating and playing with this test, i'm not so sure.

it's based off the previous attached tests, but has 5 elements that can be
locked and unlocked individually. there is a definite deterioration of
performance with multiple fixed elements. the most noticeable way i've found
to test it is to turn on smoothscroll, and use the keyboard arrows one line at
a time. with everything unlocked, it scrolls almost instantly. lock one box,
and it slows down noticeably, but not terribly. each additional locked box
seems to slow it down more. another way to test is to hold down the arrow key
then see how much it "coasts" after you release. with all unlocked it should
stop instantly.

tested in firebird 0.6.1 and 0.7 on windows 2000 sp3, pII 400mhz, 384mb ram,
16mb agp riva tnt. haven't touched a new build since 0.7, so i couldn't
comment on the recent WFMs. my computer is 5 years old now, and i wouldn't be
suprised if any newer computer with sufficient horsepower never saw these
problems.

while testing, i also uncovered another issue:
increasing the text size (CTRL +) with fixed boxes destroys performance even
more. oddly, decreasing it doesn't seem to have an effect. not sure if this
is a general thing or something unique to these testcases.