Ahhh. Well what’s better overall is gonna be fairly subjective. Php in itself was made for serving web pages with dynamic content. It came first so there’s a lot of resources to learn it, more established libraries, and there are more people who know how to code with it. Ernest having experience with PHP is likely a big contributor in his choice to use it
Rust is more efficient in terms of performance because it’s purpose was to replace C, a language that is “close to hardware” (not really but for the purpose of this explanation just assume it). Meaning a coder can deal with things manually that PHP normally does for them. This is a double edged sword because manually doing things allows you to find efficiency in things that something like PHP would miss, but it also gives a lot more opportunities to mess something up.
So in terms of performance I would say
Perfectly Written Rust > PHP > Badly written Rust.
The subjective part comes from how well you think the Rust is coded in Lemmy. So just choose which one you like more.