Drawdowns fps when knocking down fences (Forza Horizon 4)

The actual problem in the title. The game itself is the maximum speed at 70+ fps (x4 msaa +fxaa), but when the race any car hit the fence at the edge of the track (brick fence) and he shatters to pieces the fps sometimes sinking to 40, and finally 25. The problem persists even with the minimum graphics settings. Fps was 140 knocked the fence 40. PERC fx 8320 vidyuhi rx590 16GB operatives