virsh save is very slow

As reported here: http://www.redhat.com/archives/libvir-list/2009-December/msg00203.html

"virsh save" is very slow - it writes the image at around 1MB/sec on my test system.

(I think I saw a bug report for this issue on Fedora's bugzilla, but I can't find it now...)

Confirmed under Karmic.