Sorry for the length requirements for threads in this forum. I meant to suggest all Cubase Pro 9 Mac users to use Quartz Debug to test the UI responsiveness and fluency of Cubase Pro 9 on macOS.
Steps are available from Apple Developer Library, "Testing and Troubleshooting High-Resolution Content":
https://developer.apple.com/library/con ... sting.html
The only thing you need to test is the FPS fluency. If you have a fairly good graphic card like NVidia GTX 950 or AMD Radeon R9 M380, the FPS of a typical macOS app is not supposed to have FPS bottleneck less than 60FPS (even though under 4k or 5k resolution).To download the tool, please use your Apple ID to visit:
then search and download the most-recent version of "Graphics Tools for Xcode".
After downloading the DMG package, you could extract the Quartz Debug tool from it.
I wanna kept my test results on hold until I see certain amount of people meet the similar results of mine.
Please also share the model of your Mac with exact model number (and your hardware components, especially if you are using Hackintosh), the macOS version, and your possible display resolution with HiDPI status (enabled or disabled).