How to minimize Firefox memory usage

I don't know for what reason, but on my computer, Firefox tends to eat a lot of memory. And I mean A LOT. Like between 900MB and ~2GB. And I have 4GB in total, so obviously, that sucks.
So, I Googled a little and found a solution that so far works for me.
The tutorial found on this site has 2 parts, but on Linux, I think that only the second one works. So. Do:
1. In the address bar type: about:config
2. Search  browser.cache.disk.capacity in the filter.
3. Change the value so that it corresponds to your machine. The values are as follow:
"20000 is recommendable you have between 512Mb and 1GB of Ram. If you have less than 512Mb then reduce to 10000. Default is 50000, max is 51200. source"
Mine was set to 512000, but that didn't stop Mozilla from taking whatever I have. So now I set it to 20000 and so far everything works great.
Good luck!