2000 AIs in a BP game where every AI is autonomous? Have you tried to put this amount of AI in yet? I can already tell you that movement and animation will be your biggest performance problem now. Of course it depends on details, but processing BTs won’t be your biggest CPU bottleneck.
Having said that, I’ll see what I can do.
Regarding DetourCrowds it would be ideal if you created a new thread describing what amount of control over crowds you’d expect.