I'm sorry to tell you iPhone 5 runs iOS 9 extremely smooth while iPad 4 doesn't.
I wouldn't call it "extremely smooth" by any means. I owned an iPhone 5 from 2012 to October of last year when I got my 6S Plus… the iPhone 5 was okay running iOS 9. My dad owned a 4S until getting his regular 6S, but while his 4S was quite a pain to do anything with, my iPhone 5 was… less of a pain. It was more bearable than the 4S, but it was by no means ideal. Could've been worse, but certainly not "extremely smooth."
My point was, these guys were saying that the iPad 4th generation
and the iPhone 5/5C deserve another year with iOS, saying they're perfectly capable to run another version and it's "too soon" to cut them off. My point is: they're already going to be 4 years old by the end of this year, the A6 chip was never a popular one, seeing that many devices either stuck with the A5 (iPad mini and iPod Touch 5th gen), or later skipped it altogether going straight to A7 (iPad mini 2). Apple no longer sells any A6 devices, and in the past, they've always cut off devices based on what they sell before the iOS unveiling of that year. The iPhone 5C was the last A6 device to be discontinued back last year, so that means at this point, before the unveiling of iOS 10, there are no A6 devices that Apple needs to support.
In the past with iOS 8, developers complained quite a bit of how they couldn't make apps that specifically targeted newer devices. I wasn't aware of how developers could now just target newer 64-bit ones, so, that's pretty neat. However, while the other people in this forum think that this means they could still support just the A6 for iOS 10 and let app developers just make a lot of 64-bit apps, I'm of the mentality that them now letting developers specifically target the A7 and later
further signals the end of the 32-bit device support.
But that's just me.