Still I fail to see why this "live" data takes so much space.

Besides, I'll have to take your word on that, since my 4GB macbook pro has become completely unuseable due constant swapping, but it could be completely unrelated.

At the same point as you are. I have 8 GB of RAM in my mid-2009 MacBook Pro and usually have one browser running with a number of tabs. I quickly run out of RAM and go to swap, and the only solution I've found so far is to use the purge tool that came with Xcode and manually free up the "inactive" RAM that seems to just sit there.

I can't speak about your swapping problem, but for example an uncompressed (ready to display) image with 640 * 480 resolution, 24 bits per pixel takes 900 Kb memory. The mentioned 3 GB memory consumption of Chrome equals the size of 3333 of such images, which can easily be the residue of the several days of browsing the OP talking about: 333 pages with ten medium sized images. Of course this is oversimplification for the sake of easy of calculation, the browser caches many other things besides the images, but you can see that a few GB is not that much, considering the modern "need" for that much graphics.

I have a windows machine I use for web browsing and it only has 2 GB of RAM. I often have 30+ tabs open for days on end and it works just fine - I barely get any swapping (in fact, I had the swap file turned off for a few weeks before Christmas and had no problems at all).

> A lot of apps will take more memory than they need so they can keep more data "live" and be more responsive when they need to perform actions.

Which is annoying, because it leads to double-buffering.