Earlier quoted context omitted.
I don't get this; everyone says it, but I've never seen it in smartphones. Laptops, sure, but Windows really DOES accumulate a lot of cruft, and OSX's updates never seem to improve performance. Smartphones, though? The only slowdown I've noticed is when the battery starts to go. And then you can usually tell; the device gets hot as the battery pushes up against all the ESR it's accumulated, the CPU steps back a bit..…
I've felt it on my Samsung Galaxy S4, and on my SO's Samsung Galaxy S3. Both of which are high-quality devices, not some random el cheapo smartphones. Over the course of two-three years they both went from smooth&crisp to annoyingly laggy to (in case of S3) pretty much unusable even for making phone calls. Now in this story I'm just an alchemist with no experimental controls, but then again, the experience is not iso…
I’m sure you can find a way to do profiling on a smartphone, anyway.