Once Niagara is Open the editors FPS is locked to 60 even after Niagara is closed. 5.7 and 5.8

Whenever I edit an emitter using Niagara my editor FPS drops to 60 and locks until I restart it.

Doesn’t happen with Cascade.

With an empty level and Max FPS set to 500 I can get the editor running at 260-300 FPS with my hardware with nothing running.

My default it is running at 120 FPS as soon as I open and then close Niagara even if I don’t edit a emitter I am locked to 60FPS.

I am looking for an engine option or setting that would allow this FPS to recover instead of being locked or is this a bug?