another firefox since early beta user here.
i do not remember the number of machines i installed firefox on to, but i really like that there is competition now and every version gets faster and better.
I love firefox but have suffered with the memory issues for years. Please free memory when I close tabs, or at least add a flush button so I can reclaim the 500mb it balloons to in a day or two of heavy usage.
http://blog.mozilla.com/nnethercote/2011/05/23/a-better-abou...
In my experience, hitting the GC button rarely makes any detectable improvement. Right at this very moment my Firefox instance is using about 900MB of memory; hitting all three buttons in a row (garbage-collection, cycle-collection, "minimize memory usage") brings the number down to 892MB, ~750MB of which is apparently allocated to "heap-unclassified" and the JavaScript "gc-heap".
Work on reducing Firefox's memory footprint is ongoing; the most recent effort I know of is MemShrink:
http://blog.mozilla.com/nnethercote/2011/03/10/memshrink/
...and it's beginning to make some progress:
http://blog.mozilla.com/nnethercote/2011/06/22/memshrink-pro...