[Technology] GNOME Shell, memory usage, CPU usage, and graphics

I have a "Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller" according to lspci.  It's in an HP Compaq tc4400.  It's nice.  However, it doesn't like GNOME Shell when it comes to multiple monitors.



The reason is bug 699705: "Intel Gen 3 Rendering Limits are Pitiful".  A solution might be coming under the name "per-crtc pixmaps" in a future edition of the XRANDR protocol, requiring support in GNOME Shell as well.  Basically, the way memory is allocated right now, a screen that spans multiple monitors becomes too big, and GNOME Shell can't handle it.  It used to crash; now it just takes 100% CPU to draw VERY SLOWLY.



I own a nice second monitor, and I've suffered under using GNOME Shell on just one screen for too long.  Consequently, I'm now back to just using gnome-panel and metacity, and I've noticed something weird.



When I'm using just a single monitor, using GNOME Shell, if any application (with a window, at least), uses up to 50% of available RAM (e.g. Firefox, Chromium), my system slows to crawl and starts swapping like crazy.  In theory, there's still a lot of memory available, though. 



When I use metacity + gnome-panel, whether I'm using one monitor or two, I have Firefox up to 64% of available memory (nauseating) and there's no swapping yet!



Does using GNOME Shell somehow double memory usage, double what's reported under top?