It will very likely perform as fast as the iPhone 6s due to it having to push fewer pixels.
The iPod Touch 6 outperformed the iPhone 6 despite having a 1.1GHz A8 vs the iPhone 6's 1.4GHz A8. If the iPhone 5e has a 1.4GHz A8 it will be around the same perceived speed as the 6s.
Skip to the 4 minute mark.
The iPod touch 6th gen also performs about the same than the 5s as well (actually it benchmarks lower than the 5s lol)
Perceived speed....oh boy... the fact is when you're opening up most apps, there is a completely negligible difference in time it takes to open them. The 5s, itouch 6, and iPhone 6 are all basically the same in that regard. Very few games (if any) push the A7 to the point where the A8 is a noticeable upgrade in gpu, and even then the A9 is a much bigger jump in graphics power. So if the perceived speed of the itouch 6th gen is the same as the iPhone 6s, then it will be the same as the iPhone 5s. This is what is meant by "marginal upgrades" ... The iPhone 7 will be a "marginal" upgrade over the iPhone 6 as well. For big *perceived* jumps, you need to wait for multiple iPhone generations, often more than 2, to get that leap. The fact is the A9 is much, much more powerful than the A8, yet the average person with an iPhone 6 can't tell you the difference between it and an iPhone 6s when using it for daily tasks. The difference between the A7 and the A8 is significantly smaller. It's one of the smallest jumps ever in iPhone generations. And the average person has absolutely no idea about that.
I hope this isn't an accurate rumour, for the sake of those who are looking to upgrade from an iPhone 5s
If it has an A8 and 1GB, it makes no sense to pay the price difference to upgrade for what is ultimately a lateral upgrade in specs (unless you really really need Apple Pay)
But this is like paying for the same phone in terms of power and specs, just in a new case. Are the features such as Apple Pay enough to justify what could be as much as a 500$ For some people to upgrade?
Some people just want something "new" but it's giving me flashbacks to those wasting money going from the original iPhone 5 to the iPhone 5c...
But - assuming this rumour is true - this will be good for Apple's bank account as the general population doesn't know that the A8 is a small bump over the A7, especially when it comes to every day use (what the CPU drives and where the A7 and A8 are almost identical right down to the core) and will probably rush out in droves to purchase this phone without realizing they're buying, in essence, the exact same thing.
It makes more sense to the casual consumer on an iPhone 5c or 4s perhaps, or using even older iPhones. But for those with the 5s, this rumour's claim does not hint at an upgrade, the way one should expect. At least with the iPhone 6 people who upgraded got the larger display.