So I sat next to him and we started examining the UI changes in detail. And Cabel was zooming in and out instantaneously. I was like, “Whoa, how are you doing that?” And Cabel was like, “You don’t know about the Accessibility Zoom gesture? Here, let me show you!” And my mind was blown. Cabel emphasized the importance of going into the “Advanced…” dialog to turn off “Smooth images”, and I agree. This is a fantastic feature, but Apple has the default setting wrong for smoothing (a.k.a. blurring) the zoomed image. I honestly can’t imagine why anyone would want the zoomed image blurred.
Source: Daring Fireball: MacOS Tip: Enable the Zoom ‘Peek’ Gesture