Ai character hit on performance

I 've got the need to put about 50 pedestrian entities on an exterior scene, for the base ai entity i use the character class blueprint and a custom ai class that inerith from the base ai controller class, the class of ai got a simple task
get a random point and walk to that point, i’ve got a timer that check if has passed a certain ammount of time, if it is true then get another random point to walk to and reset the timer.
this simple task impact on the frame rate between 10-15 frame per second.
Is there something i should know about?
I’m sure it is not the number of triangles because the models have 3 lod wich the smallest has about 800 triangles
and when i detach the ai from the character class the counter regain those 10-15 frames.

A late recommendation. I use hundred of AI controlled NPC´s with behavior tree and perceptions. To make this to work without network and server performance hit, some actions have to be taken.

  1. Use NPC trigger volume, telling players are around, and enable/disable AI accordingly.
  2. Enable/Disable AI with SpawnDefaultController/Unposses.
  3. Hide disabled NPC´s.
  4. Enable/Disable ticks for NPC and all it´s components.
  5. Set NPC mesh draw distance.
  6. Consider to disable dedicated server tick´s and set tick interval to other then zero.
  7. Sometimes you may have a low rate timer to replicate values instead of movement replication.
  8. Let client do calculation along with server for smooth effect, server correct client with low replication rate. i.e. a ship increase/decrease speed according to +/- difference from server.