TL;DR

The power saving on the iGPU is causing the lag, force the GPU to max frequency all the time with

sudo intel_gpu_frequency --max

On Arch Linux you can get this tool from intel-gpu-tools.

The story

I bought the Morefine S600 Apex Engineer, which runs an Intel i9-12900HK iGPU. It’s my first system that only has an Intel GPU, as my previous one had the Optimus setup that included an nVidia GPU.

I guess the fix I talk about here is relevant to any Intel iGPU that uses the i915 driver, but I’m not 100% sure on that.

The CPU has a lot of power but when running a display at 4K, I’d notice a slight amount of lag (in desktop tasks, not 3D) all the time and sometimes it would stutter/lag and get worse briefly.

I tried a bunch of changes including bumping the CPU TDP and tweaking the power management profiles to make the CPU more “performance” oriented, but nothing made a difference.

When I watched the iGPU load with intel_gpu_top I’d see the frequency drop to single digit MHz numbers, which is pretty low when the max is 1300MHz. On a whim I tried this command:

sudo intel_gpu_frequency --max

…to pin the iGPU frequency to it’s max number and that was the fix!!!

It’s a relief because the rest of the system performs great but this constant slight lag was driving me nuts.

I don’t know how to make the change permanent though, so you’ll have to run the command after each boot (or X11/wayland login).