I don't use Chromium (don't tell me I don't need a menu) but in Firefox the user profile gets clogged up with cruft about once a year. A quick test is to just make a new profile and see if it's faster. Then copy over your bookmarks and gradually reestablish your cookies which keep you logged into sites between sessions by manually logging into each one.
You can get to Firefox's profile manager with firefox -ProfileManager at a command line. It's probably in the GUI somewhere. I use Chromium about once a year, don't know much about it. -- Credit is the root of all evil. - AB1JX
