Ubuntu KVM VM low Refresh Rate GUI

Above screenshot is the Graphics properties of the underlying physical host of the VM.

The VM template has been created using Opennebula Ubuntu 20.04 marketplace Public Image.

Inside the VM the Graphics properties are showing, as Cirrus Logic GD 5446

The real issue is, I have installed KDE Plasma for GUI, but the refresh rate is very low. Just to scroll down a webpage the glitch is very high.

The VM is powered by a very high Intel Xenon CPU and Ram. So resource is not a problem.

Can anyone please help to make the desktop experience smoother?

There is a way to change the VGA adapter, but xRDP really slow. It seems like the problem is with xRDP.