There are many different ones you could measure. But probably a good start is the compiler bootstrapping time.
The most important thing though is to use dedicated hardware to get consistent results. Doubt GitHub Actions will be very consistent here.
- Which metrics we should collect for each commit if building a Gi... xflywind
- Which metrics we should collect for each commit if building... Clonk
- Which metrics we should collect for each commit if buil... dom96
