I have reported this issue for some time now and don’t understand why it’s not being addressed at this point. It seems many on this forum have noticed similar issues for some time now. When using Cubase 8 or 9 on the Mac OSX Mavericks (10.11.x) or Sierra (10.12.x), there is an incredible lag when working with Cubase whether it be selecting tracks, audio clips, resizing, zooming etc. I can confirm that this issue does not exist (or at least no where as bad) in Yosemite (10.10.x) and the same versions of Cubase. I have done extensive testing on multiple Mac computers (desktops & notebook) with various displays and hard drives (SSD & mechanical) and have been able to reproduce the same results every single time. Cubase 9.0.3 unbder the latest version of Sierra (10.12.6) has still not corrected this issue. Why? I had been told about a year ago that the development team in Germany was looking into the issue. Except, Mavericks and Sierra have been out for quite some time now, and soon to be replaced again. It shouldn’t take this long to solve such a problematic issue as this, especially when it effects the user working with the program. At some point soon, I will be forced to update the system and then have to make a choice if this is not corrected by then. I’ve been a long time Cubase user (along with many other apps on the market) and still prefer it’s workflow and options compare to the competitors, however, tings like this seriously need to be addressed. And I will repeat, this is an issue with Cubase under any Mac OS after Yosemite. So the issue did not always exist. And it’s reproducible on most Mac computers, especially the larger the project you’re working on. What’s worse is that I don’t believe Cubase 9 even officially supports Yosemite any longer (which it works much better on). I don’t really see how it could have been tested on the latest Mac OSX systems that it claims to support.