I'm curious in the ways that clojure is faster to get going and more intuitive. Sbcl and quicklisp seem like they are a bit more straight forward/stable than figuring out how to do a jvm nowadays.
I'd expect you could make the same heavy use of hashtables in either, though I suspect it isn't obvious to lean on setf so much if new to CL? That, or if you are insisting on immutable structures?
I confess I assumed that alists are probably more competitive in speed for many collections than makes sense.