If you don’t really need web history, just turn it off in firefox. A lot of what bogs firefox down (slow startup, slow action when typing something into the address bar) is because of the immensely detailed history it tries to keep for you.

Sheesh. It even keeps track of which letter sequences you type into the address bar, and which address you end up selecting (for instance, when I start to type “gm”, then I usually press the down arrow to pick gmail.com”). This is how firefox is smarter, but also slower. For me, I’m happier with the faster performance.