I recently upgraded to Firefox 1.0.6 on Windows XP with SP2, and seem to now have some issues with downloading of files. In particular, Firefox completely locks up until the file is finished downloading and that whole process is slow.

IE is much faster, so I may end up back with MS!

Anyone noticed similar problems?

Nope everything fine here. Did you try to create a "virgin" profile by starting Firefox with 'Firefox -p' ? Perhaps one of your installed extensions is the culprit.