Hello,

I have exactly the same problem :
- i-tec : USB 3.0 A/C Dual HDMI Adapter
- Linux xxxxxx 5.3.0-51-generic #44~18.04.2-Ubuntu SMP Thu Apr 23 14:27:18 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
- latest displaylink software
- Gnome
- Acer Aspire 7

Same problem here...
high cpu and mouse very slow on displaylink attached external monitor (1920x1080)

- Wavlink USB3.0 HDMI display adapter chipset dl-3500
- Linux xxxxxx 5.3.0-51-generic #44~18.04.2-Ubuntu SMP Thu Apr 23 14:27:18 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
- latest displaylink software
- Gnome (xorg) on ubuntu 18.04
- Asus vivobook S512DA-EJ315T

I tried wayland on 18.04 => same problem
I tried xorg and wyland on 20.04 => same problem
I tried on windows 10 => All is fine...

Help please !