[JJJollyjim]

They mention that compiling one crate at a time (-j1) doesnt give the 7x slowdown, which rules out the object file/caching-in-rustc theories... I think the only explanation is the rustcs are sharing limited L3 cache.

[lsuresh]

The L3 cache angle is one of our hypotheses too. But it doesn't seem like we can do much about it.