Comment 20 for bug 125970

just adding some comments based on my experience in the past few weeks.

In both Mozilla and Firebird, scrolling-speed is reduced on Windows platforms if
either of the following conditions exist:

1) The page contains a fixed element.
2) Another window (set in 'always on top') is partially or wholly on top of the
browser window. (Winamp, Task Manager, etc...)

The more fixed elements present (including windows 'on top' of the browser), the
more noticeable this slowdown is.

Other comments:

I'm still thinking this may be specific to windows, and perhaps how mozilla
paints itself under the OS. Can anyone cross-test this between windows/linux or
windows/OS X? I don't really have access to linux machines or non-uberfast OS X
machines.

I've tried to see how IE behaves, but can't get mine to display anything other
than backgrounds as fixed. Having windows on top of the IE window doesn't seem
to affect its scrolling speed at all, though.

Recent builds of Firebird slow down _much_ less than before. Neither test case
produces a noticeable slowdown at all on my Athlon 500. The texturizer page is
only barely choppy. What changed?