Made performance testing framework that runs over ~800 images and tries to load 10 times each with StbImageSharp, then with native stb_image.h called through C++/CLI(Stb.Native), then with SixLabors ImageSharp.
Here are results(total loading times):
9 – StbImageSharp - jpg: 9368 ms, tga: 1337 ms, bmp: 208 ms, psd: 0 ms, png: 51936 ms, Total: 62849 ms
9 – Stb.Native - jpg: 3175 ms, tga: 1315 ms, bmp: 112 ms, psd: 0 ms, png: 45751 ms, Total: 50353 ms
9 – ImageSharp - jpg: 75071 ms, bmp: 44 ms, png: 48527 ms, Total: 123642 ms
9 – Total files processed - jpg: 170, tga: 41, bmp: 7, psd: 1, png: 568, Total: 787
More details are available here: https://github.com/StbSharp/StbImageSharp#reliability--performance