I remember how on Snow Leopard opening the lid of my laptop instantly showed the password prompt. What are more recent versions doing that it takes two or three seconds to show a text box?
For what it's worth, the M1 Macs are instant-on. Paired with an Apple Watch to unlock, I frequently open my MacBook and just stare at my background (I hide icons/menu/dock) waiting for the prompt, not realizing it's already logged in and ready to go.
From what I remember when Big Sir dropped they're doing all sorts of weird network @#$@#$ - you turn off Wifi and unplug and they open instantlier.
Probably checking that SignIn.app's signature is valid