Extreme mouse lag on some apps, mostly WPF and UWP

Hello,

In some apps, mostly Microsofts UWP and WPF (even in Razer Synapse which is WPF I think), my visual pointer update rate is somewhere between 20 and 1 (!!) fps. I can "fix" it by focusing a different window, for example Windows Explorer where it works fine and then hope to get maybe 20 fps after switching again. I know it sounds really weird. I cannot record it because the pointer is perfectly fine in recordings...
I tried to reset all mouse settings but it didn't help.

Mouse: Razer DeathAdder Elite
OS: Windows 10 newest update
CPU: Intel i7 7700k
GPU: NVIDIA RTX 2080
Monitor: Acer Predator X34A @ 3440x1440 100hz

Windows Mouse Settings:
"Enhance pointer percision" disabled
Everything else default

Razer Synapse:
Polling Rate: 1000hz
DPI: 1800

Does anybody know what could cause that behavior?

Thanks