This is a comparison of simple Mandelbrot set compiled in four languages.

Rather than get the fastest possible time, the goal is to get a general sense of how well each compiler optimizes roughly the same algorithm implemented the same way.

The timings below are for 16000x6000 images with 64 iterations.

I generated images with 1600x600 and 32 iterations to test that all algorithms created exactly the same output. Presumably the larger 16000x6000 images should all be exactly the same, too.

While running the benchmarks I've noticed a couple of things that can easily speed up some of the code here. Mostly in Common Lisp and C++, because those are the languages I'm most familiar with, and know how to spot some "gotchas".

In the disassembly, I noticed Common Lisp's complex (abs z) is calling the C library's hypot() function. Replacing (> (abs z) 2.0) with (> (+ (* (realpart z) (realpart z)) (* (imagpart z) (imagpart z))) 4.0d0) speeds it up by almost 100%.

Despite "-ffastmath" being possibly "dangerous" for giving incorrect results, the results were "pixel perfect" for all of the mandelbrot images I checked with diff.

g++ (Debian 13.2.0-5) 13.2.0

Debian clang version 16.0.6 (16)

rustc 1.62.0-nightly (879aff385 2022-04-20)

SBCL 2.3.10.159-05f2adf1e

go version go1.21.4 linux/amd64

Python 3.11.6

The OCaml toplevel, version 4.14.1

GNU Fortran (Debian 13.2.0-7) 13.2.0

GNAT 13.2.0

Free Pascal Compiler version 3.2.2+dfsg-22 [2023/09/04] for x86_64

At 16000x6000 and 64 iterations

Note: Ada, Go and Fortran aren't buffering output, so the timing is dominated by write() system call time 😒

4.41user 0.00system 0:04.41elapsed 100%CPU (0avgtext+0avgdata 3264maxresident)k

4.78user 0.01system 0:04.79elapsed 99%CPU (0avgtext+0avgdata 3072maxresident)k

5.16user 0.00system 0:05.17elapsed 99%CPU (0avgtext+0avgdata 3264maxresident)k

7.99user 0.00system 0:07.99elapsed 99%CPU (0avgtext+0avgdata 3264maxresident)k

9.08user 0.01system 0:09.10elapsed 99%CPU (0avgtext+0avgdata 1728maxresident)k

9.60user 0.00system 0:09.61elapsed 99%CPU (0avgtext+0avgdata 54136maxresident)k

13.53user 0.00system 0:13.55elapsed 99%CPU (0avgtext+0avgdata 3840maxresident)k

16.18user 19.09system 0:35.28elapsed 99%CPU (0avgtext+0avgdata 3840maxresident)k

40.83user 0.06system 0:40.90elapsed 99%CPU (0avgtext+0avgdata 384maxresident)k

26.08user 22.32system 0:48.03elapsed 100%CPU (0avgtext+0avgdata 3152maxresident)k

33.00user 19.77system 0:52.78elapsed 99%CPU (0avgtext+0avgdata 2112maxresident)k

179.88user 0.13system 3:00.04elapsed 99%CPU (0avgtext+0avgdata 9792maxresident)k