virt-manager is my go-to. There’s also Gnome Boxes, but I’ve never used it myself. virt-manager is the best I’ve tried, personally. Both use KVM, so they should be much more resource efficient

I believe the commenter was implying that DoS would be a more accurate description, since it does not seem as if the “attack” was distributed, but it is a nitpick nonetheless. We don’t have the context to understand if multiple servers were involved that distributed the load

I’d like to introduce you to Pandora’s Pot