Following in my series of multiplayer performance tickets; AI spawning synchronization was re-prioritized in recent networking engine changes. This priority change has caused the spawning of AI's to become client-render blocking.
When an AI is spawned on the server, network and object propagation occurs to all clients. These network packets cause FPS loss on all clients on immediate reception of the object. This is due to object deserialization over the network blocking the render frame.
Investigate internally queueing and throttling network updates, or processing and deserializing updates in a separate thread prior to being handled by the simulation/render thread.