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do you have any extensions installed? but yes, i have similar experiences. here's a screen shot of Chrome:

4 tabs open (MR, ArsTechnica, Youtube, a watch forum)
4 extensions installed (Adblock, Ghostery, Xmarks, Tracktor)

FF4 is way worse. 2 tabs and 3 extensions ate 500 mb right off the bat. Safari is all right... but i don't like the tab management when compared with Chrome/FF so i don't use it much. great to see that some light surfing on the internet demands just as much, if not more, memory than when i'm working in Lightroom and Excel with rdio running in the background.

and for those commenting on fresh installs, i just bought this laptop... maybe 5 days ago? it's about as fresh as can be.

I have Adblock plus, xmarks, and speed dial. Nothing out of the ordinary. Right now Firefox is open with 9 tabs and it's taking up 1.03 Gb of real memory. I saved all tabs, quit Firefox and reopened the saved tabs and now it's taking 400 mb of memory. If that's not bloat, I don't know what is. Too bad it's the most compatible browser in my experiences.
 
@benzslrpee: You bought the computer only several days ago. That doesn't necessarily mean that you have a clean computer. If you had a Mac before and the problem existed on that one too and you transferred your entire account to the new one, chances are that you transferred whatever that's causing this as well.

Try setting up a new user account, don't be logged in with your original one, only log in with the new one from a fresh boot and see how it works (I would advise the original poster to do the same as stated above).

From what I understand, the swap-file usage shown in Activity Monitor isn't the actual used capacity, just the reserved capacity. Therefore you can't say it uses an x amount right off the bat.

About Firefox 4: I tried it out when it came out and I liked the speed and smoothness of the scrolling so much that it is now my default browser. With FoxTab installed, it can have a decent 'Top Sites' navgation functionality as in Safari.
 
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