Properly written, Swift can beat rust[1]. (Obviously the rust project could probably catch up by using the same optimization techniques than the Swift project did, but my point is Swift has nothing to envy from rust in terms of performance.)

Swift’s philosophy is “easy to use first but you can go lower if you need performance.” Rust’s philosophy is kind of the opposite. I think Swift’s philosophy is a valid, and even a more interesting philosophy than rust’s, but to each his own.

wrt. migrating to ObjC/UIKit please do post references when issuing statements like these. Possibly migrating from SwiftUI to UIKit would give performance improvements, but that has nothing to do with Swift itself. SwiftUI is actually written mostly in C++ IIRC.

[1] https://news.ycombinator.com/item?id=50178103