Firefox known famous as a resource hog, not talking about Firefox 4 but talking about Firefox 3.6 and its earlier versions. Firefox sometimes eats lot of system resources as its usage is shown under Task Manager under running processes. Memory Restart add-on for Firefox alerts if Firefox’s memory usage reaches certain threshold and you can quickly restart Firefox with a single click from the status bar.
Memory Restart shows Firefox memory usage in the status bar, by default memory threshold set by Memory Restart is 500MB which you can configure from add-on options.
When Firefox consumes user defined/default memory threshold the text in the status bar turns to red, then with a single click on it you can restart Firefox which fixes any memory consumption issues. And also make sure Firefox option “ Show my Windows and tabs from the last time” enabled so that you don’t loose opened tabs and windows after restart.
Memory Restart works with Firefox 3.6 – 4.0 versions.