[CentOS-virt] KVM guest on a specific disk

I'm deploying my KVM virtualization and I have this question.

To get my guest os best performance I would like to install my OS from CD ROM while booting in a saperate disk, say /dev/sda4 then in host os I mount /dev/sda4 as /mnt/vm. So I can install a guest OS by virt-install with synax --import, right? I didn't give it a try yet so I'd like to know if other people have done it successfully.

Will this let guest os best performance because it has its own disk rather than just a image file? and will it ocuppy the host running resources less?

Rewing