During the last few weeks, the XPCOM Cycle Collector has been added to in-development Firefox 3 code.
Despite the esoteric but appropriate name, this feature performs one single and necessary task called garbage collection: it continuously monitors how different Firefox modules use the computer’s memory, identifies when a piece of it is no longer needed by any running module and releases it back so other applications can use it. The end result is that Firefox will use less memory, something many users have claimed for for years now.
The impact won’t be immediate though. Each module will have to receive some apparently simple modifications to join the garbage collection process. However we are several months away from final Firefox 3 so hopefully a large part of modules will get in.