Yes, the resolution of that display gives problems. This knowledgebase article was created for it. With a search in this forum (‘retina’ should work) you can find the topics with other user’s experiences.
Its just to right-click Cubase in the application folder and choose to open Cubase in low resolution. A patch will probably come or maybe it won`t be fixed before Cubase 7 arrives. Anyhow, it works just as well in low resolution