Basically I used to had a Windows XP guest and works well. However after few updates of libvirtd, etc, etc, and including my stupid combination to re-add the guest image somehow the Windows XP guest run far slower.
I only notice that previously my guest saying the processor as QEMU 2.4GHz, now it says Pentium II 2.4GHz.
I wonder if someone could point out to specific way to edit settings for Qemu guest machine in Virtual Machine Manager, or even help me to find quick fix to my problem. Thanks