I’m trying to setup a Windows VM but its just terribly slow, no matter how many resources I allocate to it. Both on Virtualbox and Gnome Boxes I couldn’t figure out what was going on. Is there some extra step to make this work on Fedora ?
Are you using the spice-space tools and the VirtIO drivers?
They improved performance considerably for me.
Do you have VT-x (Intel) or AMD-V (AMD) enabled in your BIOS?
I just had a thought, have you disabled CoW on the virtual machine image?