It's all for speed.

The SoA Vector – Part 1: Optimizing the Traversal of a Collection

by Sidney Congard

From the article:

I like C++ because it offers a good compromise between writing expressive and fast code. But, I discovered a problem where I didn’t know any way to hide the implementation detail away from its use: The “Structure of Arrays” (SoA) versus the “Array of Structures” (AoS) problem.

This is the first part of a series of two articles:

• what ‘SoA’ is about and what benefits it brings (part 1)
• how to implement an SoA vector in C++ (part 2)

So let’s see what those SoA and AoS are all about...