Daniel Silverstone

I can confirm that the difference in performance is around 6x: ``` listless% hyperfine ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc rustc Benchmark #1: /home/dsilvers/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc Time (mean ± σ): 11.3 ms ± 0.9 ms [User: 6.9...

Looking locally, ca. 15ms are before main() is entered (presumably due to dynamic link time for all the libraries rustup uses by dint of being linked to curl). It looks...

@matthiaskrgr Comparing with C compilers is disingenuous since the number of rustc invocations for a similarly sized codebase will be many fewer. For example, rustup is around 130 .rs files,...

Further investigation yields: The majority of the time spent parsing the manifest is in the toml load itself, i.e. before we apply any semantic understanding to the manifest. The channel...

I wrote a simple trimmer for the manifests to reduce the toml quantity in installed toolchains. Doing that results in the following (stable is untrimmed, beta is trimmed): ``` listless%...

@matthiaskrgr Assuming #2627 goes CI-green, you might want to try the binary from there and see how it affects performance for you.

When I was playing with my dodgy PR above, I ran into the fact that `rustc-dev` appears to be present in all toolchains in all targets, like `rust-std` is. @Mark-Simulacrum...

Is setting `RUSTC` purely something that cargo would want, or is it indicative of a general thing we should consider of setting `RUSTC` `CARGO` `RLS` etc. depending on which tools...

IME having profiled it a bit, the majority of the startup time of the proxies, by a *LONG* margin, is the parsing of the channel toml. Hence I played with...

@rbtcollins good point, I suppose I'd best test there too.