[dangelov]

I recently took to rewriting what should be a very simple app from Obj-C to Swift with SwiftUI - because it's the future. The CPU usage was at 5% while idle, just for having a simple tiny pie chart that updates. Not to mention that for some seemingly basic things I still had to use AppKit anyway.

Wrote basically the exact same thing 1 day later in Swift with AppKit and NO SwiftUI and it sits at 0% CPU usage with less code complexity. Maybe in a few years I will give SwiftUI another try.

[skavi]

It’s depressing how few developers would even notice that performance degradation, let alone go back in and fix it.

[odshoifsdhfs]

Did you find out what was causing it? I have developed 'heavier' (aka 50k lines of code) applications in SwiftUI on mac and it mostly sits idle (0-1% cpu based if it is doing some regular background stuff). Heck, I just created a quick Charts based app from an online example on Mac and stays at 0,0%.

Is it possible it is re-rendering the view hierarchy due to some data invalidation you haven't noticed?

[fingerlocks]

Was this with the debugger attached? Did you do any further profiling in instruments on a release scheme to determine the cause of the cpu usage? You should be able to narrow it down to the specific sys calls.

[interactivecode]

Is this app open source? I would live to poke around and see the difference both in code and performance

[nikanj]

”Premature optimization is evil” is dogma, but you can’t keyhole optimize the architecture after the fact.

Just like cars, you can’t build a Kia Soul, and then just replace a few parts to reach Ferrari-like performance.