From my understanding functons are faster than methods because they dont "pass in" all the fields of the object, only the necessary ones: is this correct?
No. The only thing passed to a method, in addition to the parameters, is a reference to the object in question. The method then uses this reference to look things up as nessecary.In either case, any real or imagined performance hit by using one over the other isn't going to make or break your game. PCs are plenty fast now, why make prograaming harder than nessecary?