I noticed in the last week or two that Firefox was often consuming a lot of my laptop’s RAM. Even though I have half a gig of RAM on this machine, Firefox was often grabbing most of the available RAM, causing other applications to occasionally stall, or at least cause the system to slow down a bit. (Will tells me this isn’t actually a slow-down, just the system degrading as it has t swap files to disk; were I on a desktop with a speedy hard drive, I probably wouldn’t notice. But I’m on a laptop with a slower hard drive, so I do.)
After a bit of Googling, I found this thread on MozillaZine, an online support site for Firefox. In another about:config hack, this one helps you force Firefox to behave a bit better when it comes to system memory. I followed the directions to limit Firefox’s available RAM to 16 megs, and this seems to have significantly improved performance. (By significantly, I’m guessing that page loads have decreased by another 30-50%.)
In other words, the improvement is noticeable. Will update if I see any negative impact, but so far this seems to be a great tweak.