Author here. There are certain performance issues, in both loading time and memory consumption. There were efforts to make Clojure runtime smaller, but they are kind of suspended for now.

I revived my old lean compiler code and for basic Hello World application on my OnePlus I reached 2.8 sec startup time and ~10 MB heap usage. I consider this a good start if further optimizations are applied (like treeshaking), but in this I rely on community (and specifically Clojure/core team) to pick up the idea.