I have had a lot of problems with Firefox 3.5 and 3.6 hesitating to open pages. Normally it goes to the pages okay, but when it comes to actually opening the page, something is not happening, and I need to mark the address and hit Enter again. This is especially true when a lot of flashy things are on the page, but I am not sure it is a security related thing. It also happens on a site that is added to trusted in Outpost. (Why can't I black- or white- list sites in Firefox, like in IE ?)
I have not had any problems with the password manager.