[RESPONDED] Very slow when using external displays

I’m running Ubuntu 21.10 on a framework DIY, and for the most part things are wonderful and lightning fast. However, when I connect to an external monitor, everything suddenly slows to a crawl. Launching applications, switching workspaces, even just typing this post is noticeably laggy.

I’ve tried a few tweaks with minimal success. No difference between connecting the monitor with HDMI vs a USB3 hub. I’m using X11 as Wayland was causing cursor lag and low-res display of some applications. I have also modified /etc/X11/xorg.conf.d/20-intel.conf to reduce screen tearing, using some subset of the following options:

Option "TearFree" "true"
Option "AccelMod" "uxa"
Option "DRI" "3"

Enabling all of these options leads to the best video display quality but also the worst lag when connected to an external monitor. I am currently only using the DRI option, but there is still lag even when I don’t include it.

Any ideas would be greatly appreciated!

I’m not familiar with those options but FWIW I use an external monitor every day and I have not configured anything special (and I don’t experience tearing or anything). I’m on Ubuntu 20.04 though.

For both OP and @gmv - do you use both monitors at once or close the lid when the external monitor is connected?

I use the internal display and an external USBc display (Thinkvision m14)

Welp, I just figured it out. I had fractional scaling on for the built-in display, and turning it off resolved all my problems. If you’re experiencing something similar and you’re using fractional scaling, that may be part of your problem!

To answer the question above, I’m using the built-in monitor at the same time as the external.


It happens to me also but only when using Single Display (External). If I use Join Displays options, it works smoothly on both laptop’s and external display.

First and perhaps mostly important, 21.10 was EOL in July of 2022.

If that was a typo and you meant 22.10, then it’s definitely worth running.

sudo dmesg -t

to see if anything stands out immediately after connecting and disconnecting the display.

Is this a 11th gen or 12th gen Framework?

Is the extent of the tweaks made? Removing these options (as they are not the prescribed defaults) change the behavior at all?

My first question is this HDMI from an expansion card to a display (no adapters or other stuff like that) or is this through a hub? You indicated HDMI vs a USB3 hub, so I wanted to make sure I understand how this is connected.

Assuming the cable is good, best results will be:

  • Direct connection using expansion card (HDMI or DP) to monitor (HDMI or DP, no adapters).

  • Temporally revert your 20-intel.conf back to its original state for testing.