It’s a pointless upgrade, anyone who was that performance starved by the i5 would not be buying this machine in the first place imo. There is those “save a second, time is money” arguements but I find them frivolous.
What counts as photo editing software? Does using OS X's Photos app count? Using it to do say, contrast/brightness adjustments to a bunch (30-50) of photos at once count? Or do you mean something more intensive/advanced?
What about managing a large Photos library within the Photos app?
I don't really do much with photos outside that app, though...