GPU usage drops drastically after first seconds of render

Hi.

I am rendering an old footage, used the coloring tab to fix things. Render settings: .mov, h264, high, slow, 2 pass full.

For some reason, after it starts the render at 95% gpu 3d usage it then drops it heavily to ~70%. Evidently, it drops the render speed from ~19 to ~10-8.

I don't run anything else while rendering. Max temp of gpu is 58c so no throttling should ever happen, fans are working just fine.

What may be the reason for that weird behavior? Any fix?

Previous to that, other videos rendered just fine, though I've never used the coloring tab before.

Specs: CPU amd ryzen 5600x, GPU nvidia 3060 12gb, 16gb ram. Resolve 18.

Bring up the CUDA charts also. And post it here.

3D tab shows what the Resolve GUI renders on screen. Minimize Resolve and every other program while rendering and watch it go close to 0%.

What you should watch is the Compute Tab and / or Video Codec / Encode. Press on one of those arrows near the names and select the proper tab.