I'm running Xorg with Xinerama across 3 monitors. And quite regularly, Xorg
will spike to 50-100% CPU usage for anywhere from 30 seconds to 3 minutes. Even when it's not doing this, I find that Xorg rarely falls below 33% CPU even if I'm doing nothing.

I suspect it may be that I'm using the nvidia driver for two of my monitors
and the nv driver for the other (I have a shiny new nvidia dual-head card and
an holder nvidia single-head card).

I've taken an strace during a spike to about 60%, and it's at
http://www.phildev.net/x.strace.gz

My video hardware is as follows:

01:00.0 VGA compatible controller: nVidia Corporation NV43 [GeForce
6600/GeForce 6600 GT] (rev a2) (prog-if 00 [VGA])
        Subsystem: XFX Pine Group Inc. Unknown device 2165
        Flags: bus master, 66MHz, medium devsel, latency 248, IRQ 193
        Memory at dc000000 (32-bit, non-prefetchable) [size=16M]
        Memory at c0000000 (32-bit, prefetchable) [size=256M]
        Memory at db000000 (32-bit, non-prefetchable) [size=16M]
        [virtual] Expansion ROM at ddde0000 [disabled] [size=128K]
        Capabilities: [60] Power Management version 2
        Capabilities: [44] AGP version 3.0
02:0d.0 VGA compatible controller: nVidia Corporation NV6 [Vanta/Vanta LT]
(rev 15) (prog-if 00 [VGA])
        Subsystem: Palit Microsystems Inc. Unknown device 002c
        Flags: bus master, 66MHz, medium devsel, latency 32, IRQ 10
        Memory at de000000 (32-bit, non-prefetchable) [size=16M]
        Memory at d6000000 (32-bit, prefetchable) [size=32M]
        Expansion ROM at d5b00000 [disabled] [size=64K]
        Capabilities: [60] Power Management version 1


My CPU is a P4 1.7Ghz - while not top-of-the-line, a reasonably modern CPU nonetheless. In addition I have 1GB of RAM.

This box does little other than have firefox, pidgin, thunderbird, ssh, and
30+ xterms, so it shouldn't be very taxed. I run fluxbox, so there's no heavy
window managers, no xgl, compiz, beryl, or fancy effects of any sort. I run my
graphical environment fairly stripped down.

Let me know what other information I can provide. Thanks.