I am not exactly sure, but comparing Ferron 1.0.0-beta5 and Caddy 2.9.1 in a benchmark where HTTPS, HTTP/2 are enabled, and default Apache httpd page was served, Caddy used so much memory, that at 12,600 requests per second the system with 16 GB RAM ran out of memory, while Ferron didn't use that much memory, and benchmark succeeded up to 20,000 requests per second. Maybe it's a bug in Caddy?

It also can be Go issue. Garbage collector did not have time to free memory.

Either that or misconfiguration with the benchmark setup. A quick google search indicates this can happen with some setups. Maybe try looking at other Caddy benchmark code.

Almost certainly given that pretty much all Rust webservers are, and this one is built on the same dependencies as others.

I run a few websites on fly.io VMs with 256mb using Rust servers that never actually exceed 64mb of usage.