Is there any way to increase character movement component performance?

Hello!

I ran into a problem with character movement component.
If I spawn big amount of AI characters with it (more than 20) it starts to inflict heavy on game performance.
Is there anything I coutd do to reduce load?

You can, but there are compromises to be made. Try setting the Default Land Movement Mode to Navmesh walking, that will make the character use navmesh for movement.

There is some interesting discussion here about it as well: Purpose of Project Navmesh Walking? - World Creation - Unreal Engine Forums

Did not spot any difference between nav mesh walking mode and usual walking. But turning off overlap events on capsule and mesh gave me more than 10 fps boost (a little bigger than 2 ms in game thread).