I’m currently running a few VMs using libvirt under Fedora 19. One problem I ran into with a new workstation was extremely sluggish performance. After consulting the interwebs, I found this great article.

• Is your architecture dependent kvm module loaded (e.g. kvm_intel). If not, and you can not load it check your BIOS settings if visualization is enabled.
• Check your VM details under “Overview” which hypervisor is in use: kvm or qemu? Choosing kvm will most likely speed things up.