Resolution control on my mac mini + 3rd party 4k monitor works just great, you can choose to have native resolution, 'retina' (i.e. 2x scaling), or a few steps

Resolution control on my mac mini + 3rd party 4k monitor works just great, you can choose to have native resolution, 'retina' (i.e. 2x scaling), or a few steps in-between the two, there's plenty of flexibility. Plus, the way it works means that (as I understand it), programs don't really need to do anything to support all these variations. Behind the scenes, the OS renders everything at a very high resolution, then uses the graphics hardware to smoothly scale everything down to your chosen size. My eyes aren't good enough to use the native resolution, and using the 'retina' setting wastes too much screen real estate (I mean, that's why you buy a big monitor for, right?), so having somewhere between the two is essential. I was concerned that choosing a non-simple scaling (neither doubled or native) would make things blurry or slow, but it just works, and works well. Even dragging windows between a high-DPI and normal DPI display is seamless. As an aside, after years of using a low-res monitor, with tiny fonts to squeeze as many terminals and emacs windows onto my screen, high-DPI is a godsend. For a long time after getting the 4k monitor, I'd just play around with the mac's screen zoom accessibility function (uses the mouse wheel to smoothly zoom into an area of the screen) - it was astounding to me just how much you can zoom before individual characters become blocky. They used to be drawn as 8x8 pixels and now, to my aging eyes, each letter looks as smooth and detailed as printed text!