Confirming same issue here.
Running Ubuntu 20.04, with a StarTech DK30C2DPPD dock (DisplayLink chipset: DL6950) and ThinkPad E590 and DisplayLink drivers 5.3.1.
When connecting via the dock to an ultrawide monitor (LG 38 inch), with native resolution of 3840x1600, it is
extremely laggy - every mouse click action takes 3-5 seconds - it completely unusable.
If I switch back to just use Laptop display (dock still connected, but monitor setting set to laptop screen only), everything works perfectly fine.
CPU load seems a bit high, but not massively high.
When on Ubuntu 19 and using the previous driver, I had exactly the same issue plus CPU was even higher (htop was maxing all threads at 100%).
I have set the logging to 1 (as per
https://support.displaylink.com/know...-of-messages-t) but made no difference.
Have also amended the 20-displaylink.conf as per a lot of other threads, again with no difference.
On a smaller monitor (34 inch with native resolution of 3440x1440), it performs better but still unusable.
Keen to see if DisplayLink update the driver soon.
UPDATE
With EVDI logging set to 0, DRM logging set to 0, pageflip modsetting applied (
https://support.displaylink.com/know...ent-x-upgrades) AND (important AND), the external monitor set to extend mode, the lag is significantly reduced - almost usable!
If I change the display settings to external screen only (i.e. single display, laptop display off), then the massive lag instantly returns.
So, the primary (laptop) screen needs to be on and active for the lag on the external monitor to be 'acceptable'. This seems like a really strange bug.
Anyone else experience this?