If you need more graphical performence then you have to passthrough your gpu to the vm by using libvirt… not easy for a newbe, but can be done… you will need to have 2 gpus or at least a recent intel gpu which can passthrough to multiple VMs.
https://wiki.archlinux.org/index.php/QEMU/Guest_graphics_acceleration
Maybe easier for you could be using gnome-boxes, which uses qemu and libvirt also. You can edit the xml file there and change settings there… But the GUI is just bare minimum.
More advanced is: virt-manager …