I too was getting frustrated with Firefox. Daily restarts, things slowing down, etc. So I decided to learn a bit more about how to troubleshoot FF.
My first problem was having to shutdown and restart Firefox every time I wanted to enable or disable an Addon. Addons are EXTREMELY useful to me, both as a web surfer and a web developer. Firebug, Web Dev tools, mouse gestures, undo close tab, session savers... they all improve my web surfing experience.
So I learned about Profiles, and how to run multiple instances of Firefox SIMULTANEOUSLY each with different Profiles. This way I can run ALL the addons I want in one profile, a known-stable set of addons for daily surfing, and a set of addons for when I need to be doing web development. The fact that I can run all three simultaneously with the --no-remote flag makes this fabulous.
I took out the Firebug addon, as well as a few others, and Firefox 3.1b2 and now b3 have been much more solid and speedy than before.
The other useful thing about Firefox is the Session Manager Addon. Instead of having 4 windows each with 15 tabs open, I keep one or two Auto-Save Sessions. What does that mean? It means, I can have context-based sessions, and quickly switch between them. It even saves the text I've typed into the comment box on Slashdot but haven't submitted when I switch sessions. It means I can have a personal surfing session, a consulting session (individual sessions for each client even!), a work session, and even other specialized sessions. And I don't have to save when switching -- just choose a new session, and your current session is saved and stored away, and your new session is opened exactly where you left it 5 minutes or 5 weeks ago.
Between Profiles and Session Manager (and 1Password, but that's mac only), Firefox allows me to surf quickly, do complex tasks, and work efficiently. That is why FF is my primary browser. Sure Chrome is super-fast, and so is Safari 4, which I do use in addition to FF for simple surfing. But at the end of the day, the powerful addons are what make Firefox rock.