Ten years ago, BeOS booted in ten seconds without any special tricks. That was on late 90's and early 00's hardware. Certainly it didn't access hundreds of megabytes of libraries and files in order to boot as a modern Linux does, but it was also specifically designed that way even by the contemporary standards.
And don't get me started about the 16-bit era... Machines were slower then but using them was generally faster.
That's why people love tablets and smartphones. You're much faster using them to check your mails or weather, etc than using a topnotch PC.
[Now of course that doesn't include booting but when did you reboot your tablet or smartphone the last time?]
And don't get me started about the 16-bit era... Machines were slower then but using them was generally faster.