These tests are being extracted from an editor project I work on. The tests themselves use the OSSignpost API for high-precision measurements combined with the XCText infrastructure for driving the UI and capturing the measurements. I've been using this combination for performance testing for a while now. It can be flakey a bit, but that's kind of the nature of UI testing sometimes. Still really great when it works.

The only truly interesting test is one that creates a 1 million line document, measures the loading time (extremely fast) and then measures the time it takes to navigate to the final line in the document. This exercises the layout system. It's really fast. On my machine TextKit 1 can do it in about 70 ms, and TextKit 2 in around 10. This isn't quite good enough for 120 fps UI on macOS machines that support it, but it's really close.

Live scrolling and window resize are both things I'm really interested in testing. But, the UI automation framework doesn't, as far as I know, have good ways of driving those interactions. But I may be able to cook something up. Ideas welcome!