In Unreal, handling a huge crowd might be challenging, especially if you are going to have a complicated system. In fact, a crowd system needs to run fast and make the crowd behave realistically.
Having a huge crowd that built-in systems don't scale properly means that you are probably basing (almost) your entire gameplay on the crowd. In this case, you should go for implementing your own Crowd system, even by modifying the built-in one. However, for most games, the built-in systems are more than enough.
In Unreal, there are two built-in systems for crowd simulation/management. These are as follows:
- UCharacterMovementComponent's RVO
- Detour Crowd System
Although it is possible to keep them both running, it is not advisable to do so. So, be sure to use the one that suits your needs the best, or create your own.
