Restrict the amount of RAM used by Firefox.

This trick will restrict the amount of RAM which is dedicated Firefox and equivalent to the number of windows you have open in Firefox. Here is how to do it.

Step 1: Type about:config into your location bar and hit Enter.

Step 2: In about:config, right-click on the new page and select New | Integer.

Step 3: In the pop-up window, type in browser.cache.memory.capacity.

Step 4: In the following pop-up window, specify how much RAM in kb you want to dedicate to the cache. You don't need an exorbitant amount, maybe between 16Mb (16384kb) and 64Mb (65536kb) maximum. If you keep it too low, performance will suffer, whereas too high would be excessive. So follow the middle path.

Step 5: Restart the browser.

It's strange as to how there wasn't a default setting in Firefox for this! Maybe Firefox was designed to use up as much RAM as it needs which may explain the bloatedness after long operation.