Arch Linux

Description:

This issue is somewhat related to https://bugs.archlinux.org/task/70516 but different enough so I'm filing a separate report here.

- After I unplug my external display (connected over USB-C, if it matters), the system gradually slows down and all operations take a significant amount of time.
- For example, opening a new browser tab takes a few seconds (both firefox and chromium), opening rofi and dmenu also takes a second or two.
- When the xrandr display is turned --off, the problem gradually goes away.
- During this time, memory (mostly virtual, but sometimes RES as well) and CPU usage of graphical applications (mpv, dmenu, rofi, firefox, X, i3) is somewhat high. However, no individual application is an outlier.
- The issue is not specific to any of the graphical applications. I can reproduce it almost consistently with each of those not running.
- I have recorded strace'ed invocations of a dmenu based script with timings for each syscall. In my cursory read, no specific syscall seems to slow down disproportionately compared to the others. However, I'd be happy the attach the logs here if anyone wants to investigate.

Additional info:
* package version(s)
- linux 5.11.14.arch1-1
- intel-ucode 20210216-1
- xorg-server 1.20.11-1
* config and/or log files etc.
- nothing in dmesg/journal/xorg logs
* link to upstream bug report, if any
- na

Steps to reproduce:

1. Connect external display over USB-C and enable it with xrandr.
2. Use the machine for a little while.
3. Unplug the cable but don't disable the display with xrandr's --off.
4. System gradually slows down.