So I have experienced the same issues with sky go being really jittery and not running smoothly with having 150mb/s download speed.
SOLVED - Work around
After a lot of research I realised sky go minimum spec is: that it says windows 7 with aero theme enabled or higher windows 10 does not have aero which is where I think the issue is. I know it's a bit of work and not everyone knows how to do it but i just partitioned my hard drive and installed windows 7 last night did all the up to date, updates and installed sky go app enabled an aero theme and hey presto I've had absolutely no issues since..