When scrolling a basic NSScrollView there seems to be a sudden jump after each flick. Scrolling does not appear smooth and is disorientating.
A scroll jump seems to happen directly after letting go of a scroll flick using a trackpad/mouse. Right at that moment the scroll turns into a momentum scroll, slowly decreasing the speed. But the first frame after the gesture the content jumps forward, more than what is expected.
Observations:
Counterintuitively, scrolling appears to be smoother when disabling NSScrollView.isCompatibleWithResponsiveScrolling. If disabled using a custom NSScrollView subclass there is no large jump anymore.
Scrolling also appears to be smoother using a SwiftUI ScrollView. I assume that has the same behaviour as a disabled isCompatibleWithResponsiveScrolling
Ironically a WKWebView scrolls much smoother. No sudden jump is observable. It also seems to scroll with faster acceleration, but the individual frames do appear smoother. Why is this better than a native NSScrollView?
Elastic scrolling at the bounds of the scroll view also appears much smoother for WKWebViews. When pulling to refresh there is a jump for NSScrollView/SwiftUI, but not for WKWebView.
When using an NSScrollView with isCompatibleWithResponsiveScrolling disabled, scrolling appears just as smooth as WKWebView on macOS 13 Ventura and below. On macOS 14 Sonoma scrolling behaviour is suddenly different.
Please see a sample project with 4 different scroll views side by side:
https://github.com/floorish/ScrollTest
Screen recordings show the sudden jumps when scrolling and when elastic scrolling.
Tested on Intel & Arm Macs, macOS 11 Big Sur through 15 Sequoia, built with Xcode 16.
Should isCompatibleWithResponsiveScrolling be disabled on Sonoma+? Are there any drawbacks?
There is also no overdraw anymore since Monterey, as described in https://developer.apple.com/library/archive/releasenotes/AppKit/RN-AppKitOlderNotes/#10_9Scrolling
Even with responsive scrolling disabled, why is WKWebView scrolling much smoother than NSScrollView?