Profiler lag

When trying to view an empty scene with just D Lighting, it has massive lag unless i move part of the window, does anyone know the cause of this?
Thanks!

Unity 2017.4.28f1

In the profile window disable the small yellow checkbox for vsync and try again. I can’t really tell from the video but it might just be a call to WaitForTargetFPS, which would not actually represent a performance spike, but a waiting for time to pass until the next vsync frame is due.

https://i.imgur.com/86bgn6h.mp4 it didn’t change anything.