Wildly unstable framerate after 3.26 patch

GPU: 9070XT
CPU: 9800X3D

On the night of league start, my performance just plummeted. Just a week ago (with identical settings) I was running a rock solid 180fps at 1440p, idling uncapped around 265fps. As of the 3.26 update, I'm having constant severe frame drops (multiple times per second, often to below 50fps, sometime as low as 13fps) from just walking around my hideout, walking through a map, using any movement skill, etc. I've tried literally everything I can think to fix it.

Uncapped, my fps only reaches around 218 now, and just moving causes it to tank. The in game graph doesn't have any coinciding spike in CPU/GPU frametime, network spikes, or shader spikes. Even dropping my resolution to 720p, I still had pretty severe hitches in framerate. Disabling MTX seemed to give me some frames back, but they would slowly creep back to unstable again within a few minutes.


What I've tried:
- DX11, DX12, Vulkan
- Turning off triple-buffering
- Deleting shader cache
- Verifying files on Steam
- Downpatching GPU drivers
- Turning off AMD smart access memory
- Disabling Radeon anti-lag
- Reinstalling
- Disabling MTX