Windows guests have 2D hardware video acceleration and 3D hardware acceleration. I doubt it will be as good as in a standalone windows computer, but Affinity works fine and smooth in my virtual machine.
In any case, it’s just a matter of installing VirtualBox, a windows version and check if Affinity works for you. It’s all free (Affinity has a 90 days trial version) and if you don’t like it, just delete it all.