Have a look at Open-World NPC optimization component for Unreal Engine that can give you a performance boost.

The component is said to provide a performance boost by optimizing the NPC out of sight of the camera. It is completely autonomous, so you just need to add it to the AI ​​(NPC) class.

There are several limitations, but it’s an astonishing system when it comes to optimizing projects, especially if you have crowded game levels with a number of characters.

Features:

• The component automatically recognizes the purpose
• Supports the single mode
• Supports coop mode (Server-Client)
• Supports dedicated servers
• The component works on a timer
• dispatchers and other settings
• The component does not affect the number of materials
• The component does not affect the behavior of your NPC and is compatible with the behavior tree.

You can learn more and get it here.