I measured ~40% improvement from 2015-05-10 to 2015-10-30. That is, it takes 0.6x time to compile. 2015-05-10 was chosen because Rust 1.0 was released 2015-05-15.

https://github.com/sanxiyn/sandbox/blob/master/rust/time-2.p...

Since then Rust 1.2 had a big focus on performance: http://blog.rust-lang.org/2015/08/06/Rust-1.2.html

I'm not sure what's considered slow or fast, but I just tried a couple of larger-ish rust projects. All data on a midrange SSD, i7 ~4.4Ghz. Warm disk-cache, so pratcically everything in RAM.

  crates.io backend service:
  # Note the thing pulls down lots of dependencies doing
  # install, so this is after a "cargo build;cargo clean":

  git clone git@github.com:rust-lang/crates.io.git crates.io.git
  cd crates.io.git/
  ./script/init-local-index.sh 
  multirust run nightly cargo build --release
  multirust run nightly cargo clean
  # 4 threads, ~100% CPU up to compiling the final cargo.io bit,
  # which takes the longest:
  git diff
  diff --git a/Cargo.toml b/Cargo.toml
  index cf99b60..02e54fb 100644
  --- a/Cargo.toml
  +++ b/Cargo.toml
  @@ -5,6 +5,7 @@ version = "0.1.0"
     
  [profile.release]
  opt-level = 2
  +codegen-units = 4
     
  [lib]
  name = "cargo_registry"

  $ time multirust run nightly cargo build --release
  real    1m29.082s
  user    4m47.276s
  sys     0m6.196s

  # Single threades (default Cargo.toml):
  real    1m41.210s
  user    4m0.376s
  sys     0m5.120s

Servo:

  git clone https://github.com/servo/servo servo.git
  cd servo.git/
  ./mach build --release

(Servo also pulls down lots of dependencies, including a full rust toolchain...)

  ./mach clean
  time ./mach build --release
  Build completed in 791.07s
  real    13m11.874s
  user    40m21.468s
  sys     0m51.304s
  

At approximately 100% cpu for the first part, either the servo build script makes sure things are parallelized, or the Cargo.toml-settings are set for parallell builds (haven't checked).

And finally, a smaller project:

  git clone https://github.com/Aaronepower/tokei.git
  cd tokei/
  cargo build --release
  cargo clean
  
  $ time cargo build --release
  real    0m30.354s
  user    0m32.708s
  sys     0m0.444s
  

According to tokei (which is a blazingly fast cloc tool), there's ~100k cloc of rust in servo, ~7500 cloc of Rust in crates.io (but that doesn't include all the dependencies...).

After doing a clean install of rust stable with multirust, the combined cloc of stuff under ~/.multirust...cargo/src and tokei is ~11.5k cloc of rust, along with ~ 1400 cloc of c++.