KVM performance with Firefox?

[Roland Koebler <r.koebler@yahoo.de>]

Hi,

I'm using KVM on Debian, and run a VM with Debian and Firefox.
Unfortunately, Firefox in the VM is *extremely* slow (and maybe
it got slower with newer Firefox-versions, but I'm not sure):
Nearly every time I open a new Firefox-tab or click on link,
CPU load goes to 100% ("system time" according to xosview)
for several seconds (or several 10 seconds), and everything
else slows down (e.g. scrolling and switching tabs does
not work or is very slow, and if I move a window, the screen
does not get updated, but a grey rectangle appears instead)
until the CPU is done. This makes Firefox more or less unusable
inside of KVM; outside of KVM Firefox runs quite fast in comparion.

I guess that it's a graphics problem (Firefox being too graphics-
intense), but I haven't found anything about this in the net, so
I'm now asking you for help:

- Is this a know problem?
- Is it a graphics problem?
  (e.g. no graphics acceleration in KVM + heavy graphics usage in Firefox)
- Is this better in newer KVM-versions?
- Do you know how to improve the performance?
- Do you know any test I could make?
- Or is Firefox simply that slow in KVM, and there's nothing to do?

Here's some information about my system:
- Host/Guest: Debian Linux 6.0
- KVM version: QEMU emulator version 1.1.2 (qemu-kvm-1.1.2+dfsg-5~bpo60+1, Debian), Copyright (c) 2003-2008 Fabrice Bellard
  (Updating to a newer Debian-package would unfortunately require to
  update the whole system.)
- X11 host dirver: "nvidia",
  graphics card nVidia Corporation NV44 [GeForce 6200 TurboCache(TM)]
- modules "kvm" and "kvm_amd" are loaded
- KVM commandline:
  /usr/bin/kvm -monitor stdio -soundhw es1370 -k de -vga std -enable-kvm -m 1024 -no-fd-bootchk -localtime -drive file="/home/user/debianvm.raw",if=virtio,cache=none -boot once=c,menu=off -net nic,vlan=0,model=virtio -net user,vlan=0 -name "debianvm" -usbdevice tablet -virtfs local,id=shared_dev,path=/home/user/shared,security_model=none,mount_tag=shared_mount


thanks
Roland