I'm afraid this should be tested to get a definite answer:(
According to the macro calling logic in ArchiCAD, the size of the arrays should matter much less than the amount of parameters and the order of parameters. Passing each parameter does a name based search for the actual parameter in the parameter list of the called macro and a copy of values. This search used to be a relevant factor in macro calling speed in ArchiCAD. This search has been improved for AC13 a lot but having less parameters will make things faster - that's for sure.
In general, I think having fewer but bigger arrays is better if the overall size is the same.
HTH,
Zsolt Táskai
ArchiCAD Development - GDL Team
AC13, AC14 and upwards...