> Anyone know what happened around 2019-09-01, when all the compile times dipped quite a bit in the graph? The dip is roughly in the center between 2019-07-01

> Anyone know what happened around 2019-09-01, when all the compile times dipped quite a bit in the graph? The dip is roughly in the center between 2019-07-01 and 2019-09-01, so I'd say it was somewhere in the start of August. As the usual suspect for speed improvements nnethercote seems to have gotten no merged PRs in that date range, I suspect it's the impact of pipelined compilation [1]. The PR that enabled it for rust's nightlies [2] was merged on Aug 1 so the date would fit quite well. [1]: https://github.com/rust-lang/cargo/pull/7143 https://github.com/rust-lang/cargo/pull/7143 [2]: https://github.com/rust-lang/rust/pull/63181 https://github.com/rust-lang/rust/pull/63181