tldr; Is there a way to achieve windows RDP comparable remote desktop performance in a KVM VM without the use of a gpu?
I have my new ryzen 3700x build running proxmox 6 as the host (debian buster). I have a windows server 2019 vm as well as manjaro kde & fedora kde spin installed. Using a windows 10 client pc with remote desktop to the windows server 2019 vm graphical performance is fantastic, youtube video’s play seamlessly in the remote browser without tearing or dropped frames its very close to local performance.
Testing both linux distros with spice with qxl enabled in the guest and with nomachine NX performance is horrendous and totally unusable. Usually the performance of NX is fantastic but it seems to be bogging down due to the lack of a gpu in the VM’s?
Thanks!
Don’t have a direct answer for you, but I have some thoughts that I figured I would share.
I know that Microsoft’s RDP solution is pretty well built, especially if you are connecting to another Microsoft operating system, as your settings and gpu acceleration are more compatible as both host systems are running windows.
When it comes to Linux remote desktop methods, I don’t think I’ve ever been able to run virtual machines anywhere close to bare-metal ‘graphical’ performance without some tearing, lagging, and so forth.
Doing some readingI found that QXL is high performance, but it is noted that it doesn’t provide the near bare-metal performance that is expected. Most people end up throwing in a spare GPU and doing PCI pass through to get those close to bare-metal speeds.
Maybe there are some others that have an idea?
It’s too bad that GPU SR-IOV wasn’t better supported all around. Then you could share one GPU amoungst several VMs w/o having to have a separate card when using VFIO. Well, nvidia has a proprietary hardware/software stack that does the same thing as SR-IOV if money is no object.
Oh, RDP… reminds me of the days when MS thought nothing of remote access until Citrix got their attention… licensed their software for NT 4.0 and then stole/reverse engineered/coincidentally copied their ideas to make RDP… 
Honestly don’t remember the details of that. Just figured it was typical MS strong arm tactics. Why come up with new ideas if you can just copy the competition, right? Joking aside it’s been a long time since I’ve used RDP but I’d have to agree the experience is a lot better than the Linux alternatives (at least those few I’ve tried).