PRs to this repo are expensive

PRs to this repo kick off automated tests (good), that build kernel source (expectedly resource intensive), and tests take over 70 minutes in some cases (this feels suboptimal). Can we make any optimizations here like ccache in runners to cut this down?

<img width="1676" height="972" alt="Image" src="https://github.com/user-attachments/assets/5962c80d-09b6-4f8b-a6ed-9bc214a2f8bb" />