Down further in the thread, BillinghamJ is seeing their iPhone 6S Plus boot in 5 seconds with iOS 10, as opposed to the 25 seconds for my iPhone 6S.
How certain are you that it's only 1 second of processing that's been removed - that's a HUGE increase in speed, that I haven't seen written up anywhere else.
Anybody else with iOS 10 on their phone able to confirm the new 5 second boot time?
I'm very nearly certain because I benchmarked decrypting the iOS 10 beta kernel using the code at [0]. The kernelcache is about 13 MB compressed and takes about 60 milliseconds to decrypt. Previous iOS versions encrypted the compressed kernelcache so benchmarking decryption of the compressed kernelcache should be correct. Unless Apple was doing something very stupid, kernelcache decryption should never have been much of a bottleneck in the first place. It is nice to see that they have found other ways to improve the boot time.