Compiler speed regressions with 1.24

Anyone else noticed compile speed regressions with stable 1.24? I went from 1.5s to 2.6s with one of my little projects - and incremental compilation does not help much. I appreciate that the focus is on total build time for larger crates, but it’s annoying for little projects. I’ve reverted to 1.22 for a while - can always use Nightly for incremental if I need it. Edit: sanity can be restored with [] incremental=false.

Is you project open or something we could look at on a private channel? If the second, please get in touch through and we’ll find someone who can have a look in trust.

Investigating these issues is hard without a project at hand and we’d absolutely like to know.


The crate is moi - only about 3Kloc. The curious thing is that just touching gave a compile time which was still significantly slower than incremental=false. (Does depend on libmosquitto1 in Ubuntu)

Update - source of some confusion was per-directory overrides still hanging around. I do get some improvement with incremental, after all! (but only from a simple file touch alas)

I can confirm this with my builds on travis:


  • rustc 1.22.1 = 20min39sec
  • rustc 1.23.0 = 18min28sec
  • rustc 1.24.0 = 23min10sec

But well… its travis so I don’t think that’s a reliable value.