Hi
I noticed when I “untick” all the define locations in Media Bay - Cubase 8 runs much smoother.
Wish there could be a way to switch it completely off. As in “disable” it completely.
Scan folders only when media bay is open still not the same results as above.
For those who do not use Media Bay I would recommend unticking all drives. 
MBR
That’s weird… Does anyone know something about?
I mentioned the same problem with Cubase 8 here: (mine is 3rd post from the bottom.)
Once I unticked everything and then just ticked the one folder I needed my performance went way up. I think the Cubase 8 install resets everything to default and it wants to search your c: drive.
Switching Media Bay off helped with the GUI lag I was experiencing when zooming vertically in/out (would always hang for a second as the zoom handle passed near the halfway point). So weird that one would affect the other!
Hasn’t cured it completely, but has cut the stutter down to less than half a second.
Anybody else ?
What is the status in your prefs of “Scan unknown File Types”?
Unticked
I keep C: USERS/DOCUMENTS/STEINBERG & VST3 PRESETS (ticked)
as well as : VST SOUND