If you must use kvm/qemu, then you will find that the performance is not going to be great. (In the future, please post more details, like distro and kvm version, it might help)
Edit: forgot to add that if your qemu/kvm supports spice then you should probably try that. Also, you should try all the video drivers to see which one gives you the best performance as seen from the guest (best fps using glxgears for example):
Your best bet for guest performance under Linux is probably cirrus, qxl or vmware.
IIRC, spice uses qxl.
Alternatively, you can try to forward a graphical application to the host over the network using:
- Virtual GL - somewhat painful to setup but the 3D will be rendered on the host (so it can take advantage of your graphics card to do the work)
- Xpra - much easier but not as fast..
- NX, VNC, etc..
They all use the network to forward the display as the video driver in qemu/kvm simply does not support 3d/gl/xv acceleration..