Everyone talks about how small AVIF files are.

Almost nobody talks about what it costs to generate them in production.

I run a free image converter built on Rust + libvips. After processing thousands of conversions, here are the numbers that changed how I think about format choice.

The compression story you already know

AVIF beats WebP on file size. For photos and gradients:

AVIF saves ~50% vs JPEG (median across 600 photos)

WebP saves ~31% vs JPEG

At the same DSSIM score, AVIF produces files ~50% smaller than WebP

Real and impressive. But that's only half the equation.

The encoding cost nobody talks about

Here's what actually happens when you encode with libaom (the default AVIF encoder):

Format Encoding time (1080p) Peak CPU Peak RAM

WebP ~90ms ~20% ~200MB

AVIF (libaom, default settings) 1–4 seconds ~400% (4 cores) ~2.5GB

AVIF (maximum quality) up to 48 seconds - -

In my tests, AVIF encoding with libaom was up to 47× slower than WebP at comparable quality settings.…