When you program for Android/IOS how much of the logic you write is referenced from optimized libraries and how much is your own craft? Now look at the entire Market Place / App Store and figure how many of those apps entirely rely on Android / IOS optimized libraries.
While it may be true that some may wander off the beaten path and write their Apps in OpenGL ES directly and maybe even C/C++ most rely on frameworks and libraries already built in (which are indeed optimized).
Look at Android(as an example). For the first few years of existence, the OS was plagued with issues of bad battery life due to poorly optimized code and bugs. Android 3.0 was basically scrapped as an OS due to bad performance.
iOS 5.0 had absolutely horrible battery life due to a bug. The Nitro Javascript engine isn't available outside of Safari, too.
http://soff.es/updated-iphone-json-benchmarks
...where Apple beats three community-developed libraries. But maybe it just wasn't that hard to beat them.
I'm also skeptical because I don't see how Apple has any incentive to optimise code ever. Their devices (ARM & x86) are doubling in CPU power left and right while the UX basically stays the same. The second-to-last generation inevitably feels sluggish on the current OS version...which just happens to be the time when people usually buy their next Apple device. Why should they make their codebase harder to maintain in that environment?
That's just in one very restricted area (JSON parsing) where there are TONS of third-party libraries of varying quality for the exact same thing. Doesn't mean much in the big picture.
>I'm also skeptical because I don't see how Apple has any incentive to optimise code ever.
And yet, they use to do it all the time in OS X, replacing bad performing components with better ones. From 10.1 on, each release actually had better performance on the SAME hardware, until Snow Leopard at least. They had hit a plateau there I guess where all the low hanging fruit optimisations were already made.
Still, it makes sense to optimise severely, if not for anything else to boast better battery life.
No doubt about 10.0-10.5/10.6. But that seems to have been an afterthought for the last two OS X releases:
http://www.macobserver.com/tmo/article/os-x-battery-life-ana...
And has there ever been an iOS update that has made things faster on the same hardware?
I don't think that Apple is intentionally making things slower, which is what I'm trying to say with the JSON parser (it is easy to write a wasteful implementation). But in the big picture, they're not optimising much either.
It doesn't matter either way.
For one, Apple and Google aren't that keen on optimising their stuff either.
Second, most desktop applications use libraries and GUI toolkits by a major source, like Apple and MS, so the situation regarding "a large part of the app is made by a third party that can optimise it" is there for those too.
Third, tons of iOS/Android apps use third party frameworks, like Corona, MonoTouch, Titanium, Unity, etc etc, and not the core iOS/Android framework.
Fourth, the most speed critical parts of an app are generally the dedicated stuff it does, and not the generic iOS/Android provided infrastructure code it uses.