Immutability in general isn't that big of a deal. The problem is that Clojure uses persistent trees for all datastructures, which will trigger alot of retain/re

Immutability in general isn't that big of a deal. The problem is that Clojure uses persistent trees for all datastructures, which will trigger alot of retain/release calls. Other than some RC overhead, it should work just fine. A GC would be ideal however.