Reading this press release was almost physically painful, because of how much Apple loves to use the phrase "up to". In total it appears 46 times.
A lot of those "up to"s are expressing user options, though -- "up to" 512 GB RAM means that there are configurations that include that, but also cheaper configurations that don't. That's a pretty different beast than "up to 4.3x faster performance", which means (presumably) that exactly one benchmark showed a 4.3x improvement and the rest showed less -- which is to say, means very little.
46, actually. 46. I am pretty certain that the explanation lies completely elsewhere...
(overuse of overstatements, for the sake of manipulation, perhaps? something that makes their saying unreliable this way - e.g. they forget to mention the other end of the range, or perhaps the mean, completely .... except when it is good for them, e.g. prices ... that's borderline to lying this way...)