[mikenew]

I get major lag spikes when the gpu is under heavy load (like doing Stable Diffusion inference or something). TBF I haven't A/B tested with X11, but I don't ever remember it being like that. An extra frame of latency isn't great on it's own, but the occasional spikes in lag are really irritating.

[cma]

May still happen especially if it is thrashing vram in and out of system memory or something, but have you tried lowering priority of the stable diffusion process?

[cloudwalk9]

I can also attest to horrific lagspikes on an Optimus laptop even if Intel is driving the desktop. Memory pressure is definitely the problem here. Lagspikes actually lessened when I switched to Wayland Gnome. I think they lessened further with PREEMPT_RT on kernel 6.12. Nvidia requires an environment variable to build on real time kernels but it plays surprisingly nice as of driver 570. But if you have this config, you need at least 11th gen Intel iGPU or AMD APU, because i915 does not build for real-time kernels. Only the Xe driver works and only if you force_probe the ID if it's Tiger Lake.

...Which I don't get because the Xe driver is said to explicitly support, at minimum, Tiger Lake. I played Minecraft on the iGPU with Xe and it was perfectly fine. It... drew 3D graphics at expected framerates.