Memory Restart is an open-source Firefox add-on that allows you to quickly restart Firefox if memory usage is too high. Firefox users can see the memory usage in the add-on bar or the toolbar tool-tip. If memory usage reaches a certain threshold, the add-on bar display and the toolbar icon will turn red. You can quickly restart Firefox at any time by clicking on the add-on bar display or the toolbar icon.
The memory threshold and add-on bar text colors are customizable. There is also an auto restart feature.
Download Memory Restart Firefox Add-on
You can download Memory Restart Firefox Add-on from here