Any way to speed it up?

### Description

So... Been using it for a few hours and it seems REALLY slow. I've got a 16 core machine, yet, watching top is showing qemu running with 1 core. I've tried setting CPU_CORES so qemu to see but that didn't work.

What are my options to give it more power? If qemu is using one CPU, should this parallelize the builds?

### Build log

_No response_

### CI config

_No response_