If you’re only dropping 10fps from a base of 30, you’re actually doing pretty great there.
Are you using NavMesh? If so, are you using Walking physics or NavMeshWalking physics? NavMeshWalking is significantly more performant for things of that nature (a lot of the principles for it were developed in conjunction with Dungeon Defenders, one of the earlier Unreal games that supported hundreds of independent enemies in world at once)
If you’re running 30fps with the engine staring at a blank screen in editor, you are in desperate need of new hardware.