as long as you don't have to live with that

same here. certainly bug in SwitfUI <-> Appkit. Bug is not reproducible when app is compiled as Catalyst for mac or when scrolling is done via scroll handle. Then everything is smooth.

same for previews and compiled version as mac app.

it is fixed in macOS 15.2 beta 3

Hmm, I run 15.2 beta3 in VM, and retested on actual code I am using with latest Xcode 16 compiling on 15.2 beta3. And it sure looks like it is fixed. There is not more a lot of hitTests in the Instruments anymore. I even closed the bug I reported for it ;)