Random stuttering on GNOME 42.9 and dual monitor setup

I have been having trouble debugging this issue for days:

on GNOME 42.9, Xorg, on Pop 22.04 and Ubuntu 22.04

seemingly randomly the whole desktop environment starts to stutter and the frame rate drops to about 10 fps, and stays that way for 10 seconds, sometimes for ever until I restart GNOME. Sometimes even after restarting GNOME it stays low and randomly gets better again.

Sometimes it happens just like that, and sometimes it happens when certain apps are launched. i.e. Gnome Extensions (42.5), maybe this is relevant, because as far as I know it uses GTK 4 and that is hardware accelerated, right?

I cannot say for certain but I am pretty sure it is not a performance thing, because sometimes the CPU is barely active when this happens. On the other hand, gnome can run very smooth event on very high CPU usage.

I am on a Thinkpad t14 Gen 1:

CPU: AMD Ryzen 7 PRO 4750U with Radeon Graphics (16) @ 1.700GHz

GPU: AMD ATI 08:00.0 Renoir


I use two external monitors at 60hz, 1920x1200 each

Both are connected via DVI to HDMI.

One HDMI is directly plugged into the Laptop, the other one is plugged into a usb-c hub with an HDMI port. (I tried two different hubs already)

Edit: Same problem when using thunderbolt/display port and HDMI ports without any hub.

The stuttering only seems to happen with the dual external monitor setup (lid is closed and open).

I don’t know how to rule out sources of the problem. could be GNOME, could be the USB-c port the Hub is connected to. could be a general HDMI issue. Could be that the Thinkpad is a crappy model in general.

I am using the dual monitor setup without problems on another mini PC on Pop 20.04 and NOME 3.38, but with display port and HDMI.

Any suggestions welcome.