Yeah, PC user here, and I have this problem.
Scrolling left or right is extremely laggy with more than 100 tracks. There’s also something messed up about the Channel Overview strip, which is displaying tracks I’ve hidden in the visibility menu and glitching out when I navigate far enough to intrude into that area.
Happens in both full-screen and windowed mode, on any monitor and with or without Windows 7 Aero disabled.
The meters and lists are fast and snappy as usual, it’s just navigation, selection, and opening / closing racks that lags.
The Cubase host machine has two GTX460 units installed to handle 4 monitors, so I have no idea why video performance is an issue.
EDIT: Setting “Audio Priority” to “Normal” instead of “Boost” in the device setup window seems to speed things up a bit, but it’s still laggy.
I have a feeling Steiny’s running everything in the mixer on the CPU. NO GPU acceleration. What a waste.