I have good hardware. Good enough that I should be able to playback a 1080p60fps video.

My specs are:

i7 6700k @ 4.5Ghz

16gb 2666mhz ddr4

R9 380x

I record in a 50k bitrate with obs studio using AMD's H.N264 encoder, In vegas I have GPU acceleration turned on. No matter what preview setting I use, Best, Good, Draft, even on low settings like good (half) my playback is still super laggy why is this?