Ok, so I've been using vm's for a while now. I have in my server rack 2 machines for doing them and they both run VBox for them. So one day I decided to put a 3rd box in and put CentOS on it. It introduced me to virtmanager. I decided to try it out on Slack on my laptop (Lenovo T510, Core I5, 4G RAM). I'm trying to install Slack in a vm, and it is PAINFULLY slow, as in taking ~8hrs or more for install. Anyone know any tricks to speeding this up? Am I missing something? Basically the process I used was: install libvirt, then install virtmanager, run vm. Any help is welcome.

I have no experience with VirtualBox, libvirt, or virtmanager, but I use qemu/KVM. Slow installs had everything to do with how the disk was configured for caching. On Qemu, the defaults are slow for installs, so I use "cache=writeback". Take a look at your documentation and see what caching models they support.

Are you using virtio? Are you creating your VMs with the right --os-type and --os-variant?

If it is an existing VM, you probably need to redo its libvirt configuration to use virtio, and also redo the VM's fstab (as virtio block devices will show up as /dev/vd* instead of /dev/sd*.)

Make sure the kvm modules are loaded on the host machine:

If not, try this (select second option according to your CPU):

Make sure as well that the host processor has virtualization extensions, and that they are turned on in BIOS.

Yep that last bit is important especially for ThinkPads. IIRC hardware virtualization is usually disabled by default.

Kernel modules are loaded. There is no option for Slackware with virtmanager when creating vm's. I just use generic >2.6* option. Changing the caching mode to writeback did seem to have a little improvement. Guess I'll have to keep tweaking it.