I recently updated to Firefox 3.5.3. and installed Roboform 6.9.97. (along with some other add onns). Through process of elimination came to a conclusion, that it was RF's fault.
It makes FF run dead slow (I mean, click on a login - it takes from 5-10 sec before opening a new tab, even scrolling is slow, and the memory footprint is huge - about 1,5Gb, compared to a non noticable one before.
Since I haven't had any problems with RF before, neither with FF, and haven't seen such behaviour on their forums reported, does anyone here know what could be the source of the problem ?