Javascript error

And the third issue I hit when trying to get authcache working ... when I turned it on my site is unbelievably slow to finish loading (on ie8 anyway). Page loads ok, javascript sits there for ages doing who knows what before it finishes running. Console error "Authcache is undefined".

I'm using fieldset_helper and now my page sits there for about 8-10 seconds doing nothing before the fieldsets collapse for auth users.

Might be a cross module compatibility issue of course ...