I set up a new PC from scratch with Windows 10 and Cubase 8.0.4. Now I am having this issue: Whenever I open plugins from specific manufacturers (can confirm Waves and Softube so far) and I move the mouse pointer over a knob or fader, the mouse pointer starts to flicker. It very quickly and constantly changes shape between the normal pointer shape and a double sided arrow. When it does that, playback starts to stutter.
This clearly is not related to system load, as it happens with all buffer settings and both the peak and average VST load are near zero.
It happens with all plugins of these two manufacturers that I own, and it never happens with any other plugins.
Not sure if it is a graphics driver issue. The latest graphics drivers for my CPU (i7 4790K) were installed automatically during Windows setup.