I'll be curious to see what the performance comparisons of typical Clojure programs will be. Persistent data structures tend to benefit a lot from highly optimised garbage collectors like those packaged with the JVM. And Clojure's highly dynamic style probably benefits a lot from JIT techniques too.
Still, it's a fascinating project, which I will watch closely.
jank is currently using immer for persistent data structures: https://github.com/arximboldi/immer
Very much inspired by Clojure, with a lot of time put into benchmarking and profiling.
It's too early for me to share numbers on jank vs Clojure itself, especially due to the rewrite, but my earlier jank versions were definitely competitive with AOT compiled Clojure jars.