If you don’t know the difference between display resolution and pixel density, and want to know why Retina displays work, here’s an introduction.
Retina
Would Finale or other apps suffer a big performance hit when running on a Retina 5K display?
If you haven’t seen or used Apple’s 27″ Retina 5K display, you ought to. It’s the best display that I have used.
Are there any hidden disadvantages in a MacBook Pro?
If I buy a Retina 5K iMac, will the graphics card cope, and do I need more memory?
The Eclectic Light Company 