Because the graphics are handled differently and is for some part handled by the GPU and not CPU. AsioGuard II has revealed that some/many plugins are having bugs that didn’t show up before, including some of Yamaha’s plugins.
Simply saying it is Cubase 8 fault is just too easy, You have to eliminate all other factors first.
Exactly the point and suggestion I was making. As I said before, I was in a situation almost exactly like Kevin’s and after kicking and screaming it ended up being my system and not Cubase’s fault. If your reason posting was to get feedback and suggestions on how to maybe fix your issue or at lease find out what might be causing it then there is some good advice above. In the end I hope you get it all sorted out it’s not fun when you have these type of annoying things preventing you from using what you purchased.