Comment by scaramanga

When there is nothing to do. Like with an array of fixed sized structures all you need to know is how many there are and then you can increment a pointer past any number of those objects, and that pointer increment itself can probably be compiled away to nothing.

It depends on exactly what you're measuring, you see. If you are loading data in order to do something, then the "do something" part will incur 100% of all the costs in that case. So when you subtract the "do something" part to just be left with the "load it" part, you can end up with a meaningless zero-to-do/doing-it-infinitely-fast kind of a result.

So then, what would you measure? Just peak RAM throughput? You can get that from the data-sheets :)