Comment 48 for bug 217908

Data needs to be retransfered to the server for images that need resizing or
those that are partially visible. When it's transfered once, image
manimuplation is done by X which leads to poor quality in the case of image
resizing.

I've just tested scrolling and I confirm that the feeling is as good as with
the FF 3.0 official build on a local machine (for both regular and smooth
scrolling).

There is a very slight difference when scrolling with a thin client caused by
the transfer of images between the server and client. I will limit image
manipulations to find the best balance between memory consumption and bandwith
usage (e.g. only pre-scale under a certain ratio).