Running my persistent desktops via NX I’ve noticed that my long run (week+) Firefox processes often get into memory trouble. It seems this is not the fault of Mozilla. Check the link for a couple fixes.
So if you’ve used Firefox you’ve probably noticed that it suffers from what can be described as a fairly harsh “memory leak”. The main cause of the problem appears to lie within the plugin for Flash content. There are 2 workarounds that I’ve located.
With a little bit of google here is some extra detail on this.
browser.cache.memory.capacity [Integer] (32768) – This setting determines whether Firefox uses system RAM to cache itself, improving performance. A value of 0 turns off caching into RAM (not recommended), while a value of -1 tells Firefox to automatically determine the amount of RAM to use. I suggest you manually specify the amount of RAM to be used (in bytes) to prevent Firefox from blowing out too much. For example, I recommend a value of 32768 (32MB) for systems with 512MB of RAM or more. For those with less RAM, try a value of 16384 (16MB). If you have any problems, set this value to -1.
Hacking Firefox: Speed Up Your Browser: Installed Memory vs Memory Cache Allocations suggestions.