Earlier quoted context omitted.
> MacOS in particular does an excellent job of rendering 2560x1440 to a 4K screen, and the increased DPI over a regular 1440p 27" screen is very noticeable. MacOS in particular gets amazingly slow when you don't use a 1:1 or 2:1 scaling. I too have have two 27" 4k screens and they made the machine unbearably slow. It got so bad that I now treat them as 1440p screens and let the screens do the scaling. It's not pretty…
I don’t notice the slightest decrease in speed or any benchmark going from native 1440p to 1440p hidpi at 4K. If there is a speed decrease, I can’t notice it on an M1. I’ve seen a lot of people parrot this claim or claim it renders awfully but have yet to experience any evidence. On the contrary, it’s been glorious. Edit: if you do 1440p scaling on a 4K on macOS make damned sure you select “1440p (Hi-DPI)” other you…
I don't "parrot" the claim. I've experienced the problem. It's day and night. After installing Monterey I couldn't run MS Teams on the external monitors anymore. It more or less locked up and I couldn't move the window back to the laptop screen. This was repeatable.
The whole problem went away when I selected 1440p (the "low resolution" one). It's fugly, but at least I can actually use my other monitors.