Indeed parallel building is the best way to speed up testing and leave the artifacts intact. This Is best described in the documentation for zuul. But as alexcrichton pointed out “Right now we unfortunately just don’t have capacity”.
The discussion on adding procedurally generated rollups to the existing infrastructure is at homu/issues/102. Although sofar it is mostly me working conceptually. I would love to hear what people are concerned about and what strategies they would or would not find acceptable.
Also one day I’d love to see this in rust, but those projects are still pretty far off.