Well for a bunch of parallel arrays you aren't really moving big blocks. Consider this: struct City { char *name; int popstrat[5]; float bound

Well for a bunch of parallel arrays you aren't really moving big blocks. Consider this: struct City { char *name; int popstrat[5]; float bounds[2]; }; A a memcpy on struct City would take care of eight distinct values, whereas a copy operation on a parallel arrays version would take at least three separate memcpy calls (maybe eight if naively implemented). I certainly agree with you on the weight given to O notation though.