Use Internet Explorer
If you think 20-30Mb is bad, then try 42Mb - 1 tab open on Ebuyer. Now that's a RAM hog for you.
'tis another thing that puts me off from using Firefox. That and the painfully slow loading time of the browser itself.
That said, IE can be just as bad with the RAM usage too when you load pages with loads of images. 19Mb currently with 3 sites open - BBC News, Cable Forum and Romulus 2 feedback - not too bad.