The big cores got faster, but the little ones did not.
> the performance cores are 10 percent faster... the efficiency cores are more efficient rather than being faster
https://arstechnica.com/gadgets/2023/09/apples-new-iphone-15...
Which sounds to me like a new version of the big cores, but not of the little cores on a more power efficient process node.
However, as always, time will tell.