UE4.22 - FPS running much slower than previous UE versions while spawning AI´s, why?

Hi, my current UE 4.22 project is 30 to 35 FPS, but as son as i reach an in-game spawn amount of 40 to 65 BP´s of any AI character type, game slows down dramatically to 12 FPS and even less… 7 FPS if rapidly firing projectiles while having all those AI´s in the scene.

none of my AI characters have ticks in their Blueprints, projectiles do, but problem persist while not firing, i´m using AI child Characters and also Level Streaming for scene optimization, AI meshes use default LODs from UE, what else can i do?