Abstractions are leaky - much more often than one would like to think. On modern 64-bit systems, for example, with the apparently "limitless" virtual memory one

Abstractions are leaky - much more often than one would like to think. On modern 64-bit systems, for example, with the apparently "limitless" virtual memory one has to pay close attention not only to the allocation patterns but also to the access patterns: random reads and writes from/to a huge array may lead to a significant drop in performance.