Yesterday i found out that if i switch graphics card driver to windows standard driver the problem goes away.
I have nvidia GTX 960 and latest drivers. So this is kind of counter intuitive. If I increase graphics power with proper drivers i get very bad graphics performance.
I can use windows drivers when using cubase but i have to switch to nvidia driver if i do some graphics stuff like video.
When all other programs seem to be working ok with nvidia drivers it makes me wonder is there something wrong how cubase handles graphics