This doesn't take into account the horrible sluggishness of Safari's interface, nor is it representative of Safari's ludicrous memory usage. To date, I've never seen Chrome or Firefox use over 1GB RAM, but Safari is atrocious.
Honestly, just look at this memory usage from a WebKit nightly. How is this acceptable?
That seems excessive. I'm running the latest Webkit nightly (Intel 64-bit, ver. 4.0.4 (6531.21.10, r51881)), using only 287mb of Real Mem.
Your numbers seem way out of line. I've never heard of such a thing. Were you doing anything out of the ordinary with the browser? Was there a memory leak or something?
Slightly OT:
Is it just me, or is Firefox really starting to lag behind? Seems WebKit is THE engine to use these days. I'm willing to bet that even in Beta, Chrome runs better and faster than the latest stable release of Firefox for Mac. Or am I reaching with this one?