BUT if by chance you or your project is one of the more "serious lisps or next-lisp-vibes" hear his:
Before you even think about speed or benchmarks(size,spec,speed,lang) remember we live in a connected world that is multi-core.
First prize for your home-brew lisp that would make me sit up and take notice is if it has very easy net-libraries built-in (http (client + server), websocket, sse, json etc) I think that is one of the things Go(yes I know not every like it, but the real world usage is real) got right, the std lib was very "modern" at least to the point of real-world usability. Multicore is a close second prize :)
Network-libs (stupid easy ones) and the concurrency concepts is the very first thing I look for in a lang or lisp-derivatives
My 2cents :)