I'm having an extremely difficult time editing 4k video with Vegas Pro 15. Last year I upgraded to VP15 (build 416), and purchased a new computer just for 4k editing, but a lagging preview makes this nearly impossible. I am running Windows 10, and my processor is a 7th generation Intel i7-7700HQ quad core (6 mb of ca che, up to 3.8 GHz). I have 16 gigs of RAM, and my video card is an NVDIA GeForce GTX 1060 with 6GB of GDDR5 graphics memory. I made these purchases feeling confident that I would have no problems working with 4K, boy was I wrong. My footage is from GoPro Hero 7 Black cameras, and a DJI Mavic 2 Pro drone. Anybody have any suggestions?