Help in identifying problem in profiler?

Hello…
I have this profiler recorded…

the first few seconds, for 4 times, i spawned 50 ai controlled actors with BT…
total of 200 actors…

the thing is, the fps slows down…
i think it is caused by the BT of each actors that handles the navigation / movement of all the ai actors…

i dont know how to identify problems in the profiler…
but there seems to be alot of “cpu stall - sleep” and “cpu stall - waitforevent”

i have i3-550 3.20ghz and 8gb ram
using gtx 960

the frame ms and game ms seems to just catch up on each other…
the draw ms are just 8-10 ms

the stats on statGAME
has high world tick time

how can i improve all this?
any way to improve the BT?
its just a simple movement go to and wait BT that i got from a simple tutorial…
a few actors with it is fine, but with 200 actors… it lags…

any better way ?