The benchmark is here: https://sansyrox.github.io/robyn/#/comparison
I took a brief look into the internals and turns out it wraps actix web (https://github.com/sansyrox/robyn/blob/main/src/server.rs), one of the more dominant web servers on techempower.
tldr: I dont have a good reason to doubt the performance but seems pretty interesting if you want to use actix web without having to go through rust