As with most things, "it depends". If you compile very macro compile-time virtual-machine heavy code that can be slow. If you compile to the c++ backend then that backend process can be slow. If you invoke some macro that generates mountains of Nim code translated to continents of C code it can be slow. If you use the default `nim.cfg` that has gcc -Og it can take a lot longer than gcc -O0, for example. Meanwhile, if you use the `tcc` backend even without incremental compilation it can be close to immediate feedback:

    $ touch foo.nim
    $ /usr/bin/time nim c foo.nim
    CC: ../usr/lib/nim/lib/std/private/digitsutils.nim
    CC: ../usr/lib/nim/lib/system/dollars.nim
    CC: ../usr/lib/nim/lib/system.nim
    CC: foo.nim
    Hint: gc: refc; opt: none (DEBUG BUILD, `-d:release` generates faster code)
    36891 lines; 0.154s; 39.434MiB peakmem; proj: /tmp/foo.nim; out: /tmp/foo [SuccessX]
    0.24user 0.02system 0:00.27elapsed 101%CPU (0avgtext+0avgdata 44360maxresident)k
    0inputs+0outputs (0major+13676minor)pagefaults 0swaps

(I point my default backend compiler to tcc in my $HOME/.config/nim/nim.cfg.) There are some more details in this nim forum thread: https://forum.nim-lang.org/t/8677

Unless your standards are "single digit milliseconds per file like tcc itself, please!", 240 ms is not so bad. (EDIT: And this is just on some 2016-era Intel i7-6700k box, not some liquid helium cooled 10 GHz whatever.)

It's much faster than C++, Rust, Go and many others.

I'm assuming this must be for huge projects?

I just compiled my toy project (detecting anomalous parity in integers) in nim 1.6.6 (4.23s), go 1.17.7 (2.43s to create both aarch64 and x86_64 binaries), zig 0.8.0-dev.1140 (2.04s to create aarch64 and x86_64 binaries) and C via clang 13.1.6 (0.14s).

nim's compilation is 175% of Go, 207% of zig, and 3021% of clang.

how are u compiling (optimization, custom compilation flags etc.?) In my case https://github.com/mratsim/Arraymancer big project compile under your 4.2s so or you have like 10k+ lines of codes with macros or you just pass some debug flags to compiler :D

Compilation command is:

    nim c -d:release --passC:"-flto" --gc:markAndSweep --out:ap ap.nim

I will add that once it's been run a few times, it does go a bit quicker (down to ~0.7s) but the Go also gets quicker (down to 0.28s for two outputs when files are cached.)

No, even small files. You must have issues with your setup. Are you sure your compiler is not built in debug mode?

How would I check that? I installed it through homebrew via https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/... which doesn't seem to mention debug mode anywhere?

Run `nim -v`, if it's not in debug mode you should see "active boot switches: -d:release".

Looks like it isn't in debug mode after all.

    $ nim -v
    Nim Compiler Version 1.6.6 [MacOSX: arm64]
    Compiled at 2022-05-05
    Copyright (c) 2006-2021 by Andreas Rumpf
    
    active boot switches: -d:release -d:nimUseLinenoise

Thanks for the data; that's what I call an elegant rebuttal.

No, it is not - Nim's compiler backend is extremely complex and full of cruft. I've been around Nim for 7+ years now and there's a reason the compiler was hard forked.

Nim's compiler is definitely not speedy, and this is why so much effort has been spent on incremental compilation, which tmk, still isn't working - https://github.com/nim-lang/Nim/issues/19757.

In comparison to languages like Rust and C++ it compiles pretty fast. Or maybe you built the compiler in debug mode.