Hash algorithm in javascript

I'm implementing a .pac file to do hash-based load-balancing among
different caches.
Problem is, I need to find a good hash function.
md5 would be nice, but I think it's a tad too heavy to use in a
.pac file.

Any suggestions and/or sample implementations and/or links?

-- 
	ing. Francesco Chemolli
	Unicredit Servizi Informativi