Ignoring the possibility for compression, read "cost" as the cost of executing a procedure on many instances at once. The cost decreases if you have control ove

Ignoring the possibility for compression, read "cost" as the cost of executing a procedure on many instances at once. The cost decreases if you have control over data layout. Think sorting / searching, cache efficiency, SIMD. It helps to think about relational databases (and there, why are column stores much faster for many tasks).