Clojure tries hard to figure out which type a variable may have. Then it can emit code which calls the actual method directly, which is as fast as a normal Java call would be.
However sometimes it cannot do so and has to fall back to reflection,
which is quite a bit slower. To spot these occasions Clojure provides
You can tell clojuresque to set this flag by setting the appropriate option.
warnOnReflection = true