accessing the arguments object is expensive.. huh?

Question

I\'ve heard alot of people saying that accessing the arguments object is expensive. (example: Why was the arguments.callee.caller property deprecated in JavaScript?)

Btw

Answer 1

I have also never heard a serious explanation for why accessing the arguments object is expensive. However, this site: http://www.playmycode.com/blog/2011/03/simple-yet-effective-javascript-optimisations/ notes that arguments is not really an array and is less efficient than accessing an array. The above linked site even suggests converting arguments to an array as an optimization.

Going to check with those who know JS interpreters more intimately...