My Firefox seems to be getting very laggy lately and this used to happen on my older computer when I was low on memory, however I checked and I have plenty of memory still available but it's still laggy, so I'm wondering do I perhaps have to increase the memory it's allowed to use?

By laggy I mean it has the same visual effect as lag, in that when you're interacting with the screen things "lag" / get stuck / appear slow - nothing to do with page load time.

I did a little digging and found this [almost 12 year old thread](http://forums.mozillazine.org/viewtopic.php?f=38&t=193090); so I'm wondering does what is mentioned there still apply now?

Namely, by going to `about:config` in the address bar and then adding the configuration setting `browser.cache.memory.capacity` and giving it a value of the amount of memory it's allowed to use in *Kb's*?

If not, is there a way to do this?