A few Firefox tweaks

When I'm working on a website I usually have at least one Firefox window open with several tabs.  After a couple hours Firefox is noticeably slower and scripts start to crawl, which is really a problem when I'm working on JavaScript stuff. 

I found a fairly old post on LifeHacker that lists several tweaks to speed up FireFox and hopefully help with the memory problems I've been having.

The one that I like the most really isn't a speed or memory issue, but it let's me turn off the close icons on tabs.  I can't tell you how often I've missed and clicked on a close button by mistake. 

The one for network.prefetch.next seems like it'll be a good one too since it turns off the default behavior of Firefox trying to guess and fetching pages before you click the link. 

And since I can't spell to save my life I've also change layout.spellcheckDefault to 2 so that single line text fields are spell checked as well, although that doesn't seem to be working right now.

The LifeHacker article explain it a little better than me, but you get to these settings by typing about:config into the address bar.

The post has probably a few dozen more.  Several of the commenters have left suggestions too, so be sure to read the comments.