An error occurred while saving the commentMichael Jakob commented
What I recently found out is that as soon as I have the display with the highest resolution set to "make this my main display" (Windows 10 settings: https://windowsreport.com/change-primary-monitor/), the interface is running considerably smoother (for AE terms).
Not only in AE but also in Premiere, Figma, Miro etc.
Even without the "High DPI scaling override" to system (recommended by eikonoklastes Jul 17, 2018 in the original post linked above)
I'm running a Huawei MateBook X Pro 2018 (3000x2000px display) and two 4K external monitors on an Aorus Gaming Box RTX 2070.
When I switch my main display back to my laptop screen, beforehand mentioned software works only smooth within this main screen, not anymore in the external screen.
I switch it back to the screens with the highest resolution. Smooth again. On all 3 screens.