It's SwiftUI that is at fault here[1][2], not native apps in general. I wrote my native app in Qt C++ and QML and showed that it is *significantly* faster and uses significantly less RAM than similar web apps[3]. So, no, web apps, in general, are slower and uses more resources than well-engineered native apps.
[1] https://notes.alinpanaitiu.com/SwiftUI%20is%20convenient,%20...
[2] https://x.com/daniel_nguyenx/status/1734495508746702936
[3] https://rubymamistvalove.com/block-editor#8-performance