Movable skylights must be manually refreshed via blueprint, and even then are very cheap to update, and it is completely impossible to update reflection captures AT ALL in all versions of unreal 4 without potentially heavy engine modification (Unfortunately).
My reflection capture and my skylight was Stationary. I’ve set them to static and its brought the frame time down about 3ms. I think you’re on the right track, with it being to do with my skylight, reflections ect. Maybe it’s normal to be quite large performance hit with a big scene ? Thank you for your help.