To better understand when to use the Object Pool pattern, let's review when not to use it. For instance, if you have entities that need to be spawned once on your map, such as a final boss, putting it in an Object Pool is a waste of memory that you could use for something more useful.
Also, we should keep in mind that an Object Pool is not a cache. It has a similar purpose—the reuse of objects. The core difference is that an Object Pool has a mechanism in which entities are automatically returned to the pool after being used, and an Object Pool, if well implemented, handles the creation and deletion of objects depending on the available size of the pool.
But suppose we have entities such as bullets, particles, and enemy characters that are frequently spawned and destroyed during a gameplay sequence. In that case, the Object Pool can relieve some of the strain we are putting on the CPU by reducing repetitious lifespan calls such as create...