I came across this video from Everything Apple Pro yesterday and had to share it here because it illustrates something I talk about all the time: the fact that upgrading your mobile device doesn't necessarily deliver the massive performance boost that some users believe it will.
For my purposes, you can start watching at around the 2:00 point. It's a side-by-side speed test showing how quickly the same Reddit page loads across every iPhone ever made. Each device — from 2G up to 5S — has had the same firmware upgrade, meaning that each is using the latest version of Safari.
The conclusion after the test: While the iPhone 5s is "the king of this test" because it loads the page marginally faster than the other devices, the "spike in power" you get from upgrading "isn't even that noticeable in day-to-day use".
But watch for yourself and see:
These findings are consistent with our earlier findings that, for iOS, 98-99% of response time happens after the HTML arrives. In other words, when it comes to delivering faster pages to mobile devices, your browser is king.
If you're upgrading your OS, and therefore upgrading your browser, then you're taking your phone most of the way there in terms of what it's capable of delivering performance-wise. There is arguably more performance to be gained by using a more optimized browser (e.g., smarter request ordering, optimized JavaScript engine, etc.) than by adding more horsepower.
Buying a brand-new device isn't a magic bullet for performance. But they sure do look pretty. ;)