It’s impressive that anything could run in 4K with the GPU connected by a single lane of PCIe 2.0 and the CPU translating X86 code to ARM. Maybe a future Raspberry Pi version will actually have enough power and bandwidth to make it somewhat practical.

At 4K with RTX On, the frame rate plummeted to around 12 FPS. A system utility revealed that the GPU utilization was below 50%, as the rest of the Pi system bottlenecked it so comprehensively.

The poor CPU is getting hammered like there is no tomorrow.