For the past few months, Firefox has been getting slower and slower to boot/quit and frequently needed to be restarted.
Driving me nuts. Safari and Opera run just great, so I figured it was all of my FF extensions.
I stumbled on a discussion forum of someone having the exact same problem as me...and it's fixed now. Had to delete the places.sqlite file in my firefox profile. It had grown to 350MB. Apparently, this issue is fixed in FF3.5, but since I upgrading from previous versions it brought the bloat along.
Warning: you'll lose your history and bookmarks. Not an issue for me since I use del.icio.us and xmarks.
Here's a link to forum thread I found the answer on...