Redraw when scrolling sometimes takes several seconds, while the
machine is idle. This occurs when scrolling the keyword area on
the IMDb, e.g.

http://akas.imdb.com/search/keyword?keywords=shooting-gallery

but not always. Once this happens, this always occurs, possibly
until the keyword area is no longer visible (something like that).
I've attached a snapshot of this keyword area.

Control: found -1 38.2.1esr-1
Control: severity -1 normal

This occurs very often and this is particularly annoying, as it is
so slow that it is more or less impossible to see the whole list of
keywords, and Iceweasel becomes unusable for this task.

This happens both with nouveau and the proprietary nVidia driver,
so that this is not a driver issue.

Currently, it seems to occur only when I have 5 rows of tabs (I'm
using the Tab Mix Plus extension), but not always, so that I wonder
whether this is a real cause (and I don't see why it would matter).

src:iceweasel has been superseded by src:firefox-esr in version
45.0esr-1 in March 2016. Transitional packages to ease upgrades were
provided in the wheezy, jessie, stretch and buster releases. The
transitional packages have been removed finally before the bullseye
release in August 2021.
After regular security support for buster ended in August 2022 and LTS
support ended in June 2024, I'm closing the remaining bug reports now.

Andreas