Firefox is great, but everybody knows it has an Achilles heel: massive memory sucking. I have had sessions that have eventually brought my computer down to a crawl, often after I have minimized what I was doing and then come back to it later (as you might imagine, I get interrupted around here a lot). But! I have discovered the secret to keep Firefox from getting too bloated when you minimize it for later.

Via Lifehack:

This setting will move Firefox to your hard drive when you minimize it, taking up much less memory. And there is no noticeable difference in speed when you restore Firefox, so it’s definitely worth a go. Again, go to about:config, right-click anywhere and select New-> Boolean. Name it “config.trim_on_minimize” and set it to TRUE. You have to restart Firefox for these settings to take effect.

It works like a charm!