I’ve been a huge Firefox fan, and used it almost exclusively, but recently, it’s been more of a resource hog than anything. It’s gotten so bad that my entire Mac’s slowed down because of Firefox. Sometimes, CPU usage will shoot up to over 90%, and my whole system slows to a crawl. I’d realise the lag while I was typing in Firefox (it would lag and freeze for a second while I was typing) and while I was switching between tabs (I’d notice a significant delay before the screen switches to the new tab window).
Ever since I realised these problems with Firefox, I’ve switched to Safari, mostly since it came along with Snow Leopard. It’s a bit different than Firefox, especially with its behaviour and keyboard shortcut keys, but overall, it’s been great. It feels so much faster, and my system doesn’t lag like with Firefox.
Some of my extensions in Firefox were replaced by Safari features out-of-the-box, such as the Safari Web Inspector, which replaced my Firebug for Firefox. You have to enable it through Preferences > Advanced > Enable Developer Menu though. Once you’ve enabled this menu, you can find the Web Inspector inside.
One extension that I couldn’t live without is Lastpass, but thankfully they had a Safari version! Now I’m all set again 🙂