variables passed as parameters

[Danie Schutte]

Just a quick question,

when a list / gb_tree is passed as a parameter, is a full memcopy of the data 
done to the new function? 

The reason for my question:  We would like to a have a data set passed on 
through various modules, and each module may / may not update this data..

We are trying to figure out if it would be faster to create a single module 
that manages the data in a "memory space" (like a gen_server state variable 
or an ets table) or wether it would not really matter in terms of speed - and 
the only factor to watch out for would be memory? 

Thanks
Daniel