Perhaps it’s program dependent.
I’ve read a number of articles that put the advantage Windows 64 bit had over 32 bit in the 10 to 20% range for speed, but there were some programs that had very high memory transfer requirements which were at the upper end of that range.
I’m not like those guys who pooh-poohed 32 bit systems back in the day when AMD has extra-fast 80286 CPUs. I just don’t think that the one-year headstart will make much difference except for certain programs for most users. In a year, both camps (and Windows, too) will all be 64 bit on phones.
I think that Apple will have the advantage with their iOS system, along with their new Swift programming language in taking advantage of the 64 bit processors. When looking at the specs and the processor speed increase, that’s amazing by itself ... along with the increase in the RAM to 2 Megabytes.