I have 40 tabs open now, and it's using 1.16 GB which is awesome. I actually want it to take up more because I have 6GB of free RAM not being used, which is a waste.
Compare that to chrome. Using the same number of tabs and it can easily take up more than 3GB of ram on my system, which is expected since each tab is a different process.
I wonder when Firefox's tabs will run on their own separate process. I'm looking forward to that. I think I saw some updates a month ago but I can't find that now.
(fwiw, I have 16GB of RAM)
The only thing about using separate processes is that you increase memory usage, since every tab has overhead, and tabs can't share resources (chrome tends to go process per domain).
bang, you have multiprocess firefox.
a word of warning: it doesn't work so well, so i guess it's experimetal. you'll probably want to revert to false ;-)