GPU Fryer is paused for around 4 minutes while freeing GPUs

Tailing logs:
```shell
GPU #0: 4444 Gflops/s (min: 4398.05, max: 5497.56, dev: 224.44)
Temperature: 35.58°C (min: 32.00, max: 38.00)
Throttling HW: false, Thermal SW: false, Thermal HW: false
All GPUs seem healthy
Freeing GPUs...
```
GPU Fryer is paused for around 4 minutes while freeing GPUs in some family, example: Tesla T4.

Start by reproducing the pause on a Tesla T4 while capturing the logs around “Freeing GPUs...”, then trace the Rust entry point that performs GPU cleanup. Done means the cleanup completes without the reported roughly four-minute pause and the existing health checks still pass.

Written by the indexing model from the issue text.