In my case since v0.9.38 mouse smooth and performance in overall is awesome. About current problem:
1) My problems are in slave screen. Main screen is fine
2) Mouse movement is not smooth and performance is bad ( in slave screen )
3) I haven't lag in main screen if I use good connection. If I use wifi ( bad connection due cheap tablet ) i suffer main screen performance degradation due server wait slave screen update finish for continue. Not idea why slave screen affects main screen performance in this case.
I uploaded dxdiag file. My main tablet ( surface pro 6 ) have last w10 version with all updates applied. I have drivers up to date too. As I commented with v0.9.61 performance is fantastic even using low level chinese tablet. I'm very impressed with your application
I hope this helps. I can make a video if you want see real effect.
Thanks in advance