Does your game have Seats that are often used? I am getting this same issue with ShadowMap only when either yourself or someone near to you is sat in a seat.
Is this how your Microprofiler looks too?
If any engineers are watching this thread, stopping the Animate script from playing an animation while sat will prevent this frame drop.
I’m still getting a lot of reports about this.
I’ve tried to mitigate it as much as I can, but since this isn’t an issue with my game and rather an issue with lighting; I’m limited to what I can do.