Performance concerns

There are a lot of benefits to using the Component Object Model. These days, many engines use this approach because of the flexibility it provides. However, that flexibility comes at a cost to performance. The biggest performance costs are calls to new/delete, cache coherency, and virtual methods.

Our M5ObjectManager uses pointers to M5objects which uses an STL vector of pointers to components. This means that as we create Bullets, Asteroids, Raiders, and Planets, we are constantly calling new and delete. These are slow functions and have the chance to fragment our memory. In a later chapter, we will see how object pools can help us solve both of these problems.

However, even with object pools, we still have problems with cache misses. The fact is that iterating over an array of contiguous data is much faster than iterating over an array of pointers to data. When using the Component object Model, the CPU will be spending a lot more time chasing pointers and loading that...