@Messy
hay just want to check what your drive setup is are all files on SSD's? something like
1- bootdrive 2- scratch 3+4- files?
do you have the prefes set with a dedicated scratch disc (and correctly setup)
are you on adobe CC or older
are you trying to watch the video at 100%, have you tryed 50% or 25%
what video codec
2GB vram may be a problem but depends on your workload
use activity monitor
(most people who iv seen complain had a bad drive setup, every one jumps on the cpu and ignores drives)