Apple has pretty consistently had the fastest SoCs for phones and tablets for a few years now, particularly in single core performance. Here are some benchmark results of the iPhone 12 versus some of it’s Android competitors [1]. Notice that last year’s iPhone 11 Pro Max still outperforms Android phones from this year as well.
I think part of the reason this isn’t a major differentiator (for phones at least) is that phones have been “fast enough” for several years now. Given the very aggressive throttling that is utilized on these types of devices, I think the primary difference ends up being battery life / efficiency rather than raw performance.
It’s also worth noting that while the performance / efficiency gap between x86 and ARM seems to be pretty sizable at this point, the gap between various current generation ARM CPUs isn’t nearly as drastic.
1: https://www.tomsguide.com/news/iphone-12-benchmarks-this-des...