Currently the version of ASM bundled in Clojure is pretty old (circa 2005).  There are some documented performance improvements in newer versions of ASM that should speed up some things in Clojure.

It may not be the desired approach, but CLJ-713 has a patch related to this.

Next Steps

• A Move to the latest ASM (currently 3.3.1) 
• No longer subset-ed it (Only a subset of ASM was included back when it dominated Clojure's jar size, back in those early days when Clojure fit on a floppy :))
• Still re-rooted it under clojure.asm

Future Steps

• Build an independent (but still re-rooted) clojure.asm jar, and a dep on it. That way delivery targets that don't use dynamic code gen (e.g. Android) can easily leave it out.