I think this depends on perspective. Compared to an Electron app, it's significantly better. Compared to a hand-optimised app implemented in a low level language it's not great.

I've not done a lot of Swift/iOS/macOS, but I have a passing familiarity. These numbers are basically what I'd expect for a normal app. In other words I think the relative optimisation comes from the fundamentally better technology choice rather than from being particularly careful about performance.