And that is where you get into features and versions and improvements.
Always run the latest when possible.
And the speed of the CPU of the hypervisor has a huge impact in this situation. As well as capabilities to offload to virtual or physical GPU.
The version of RDP has an impact as well as the version of the hypervisor and the version of the OS in the VM you are targeting.
RDP capabilities will be down-leveled to the lowest client version in the connection (the client and the server side determine the features). Just because it does RDP doesn't mean it has the version that gives you the performance feature you desire.
And you only get high fidelity with the version in Windows 8 or later. This has nothing to do with the version of the hypervisor.
However, features like vGPU have everything to do with the hypervisor.
I am guessing that your poor video experience is multi-fold. It can be affected by any of the following: the version of the remoting protocol, the CPU speed of the hypervisor, the configuration of the VM (# of vCPU amount of RAM - and the optimum configuration
is different for different OS releases), and storage speed if there is any caching.