Laptop very sluggish using external monitor at 3840x2160 resolution

Framework Laptop 16 Linux
1

When using my Framework 16 with the LG UltraGear UHD 32" 144Hz Monitor (32GR93U-B) connected via HDMI, the laptop can become very sluggish at 3840x2160 resolution. It’s mostly fine until I join a Zoom call (screen sharing makes the sluggishness even worse) or when using a more demanding app such as Miro. I’ve had to use the monitor at 1920x1080 resolution to make the laptop usable.

In the system monitor I can see the iGPU reaching 100% when on a Zoom call.

Is there anything I can do to fix this? Here is my full system information:

Operating System: EndeavourOS
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.1
Kernel Version: 6.12.65-1-lts (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 9 7940HS w/ Radeon 780M Graphics
Memory: 32 GiB of RAM (30.7 GiB usable)
Graphics Processor: AMD Radeon 780M Graphics
Manufacturer: Framework
Product Name: Laptop 16 (AMD Ryzen 7040 Series)
System Version: AJ

2

Idk what it is, but there seems to be some significant cost to using an external monitor, especially at 4k. I think it’s still present at lower resolutions, just less noticable:
FPS loss when gaming on external monitor - Framework Laptop 16 - Framework Community