Mac takes around 10 seconds to wake from sleep after macOS 27 update

10 seconds to wake from sleep does not seem normal.

Note that it is possible that you are being logged out instead of your Mac just sleeping. The login process is longer than the wake up process. There is a 'hidden' setting that can cause that (not explicitly hidden, but not where you might think to look).

Go to System Settings > Privacy & Security > Advanced (button at the bottom), and if the setting to Log out automatically after inactivity is on then toggle it off.

More generally:

Have you rebooted your Mac? If not, that's the first step. If that does not help, then see if the problem is present when you boot in safe mode. That process performs some system cleanup and clears caches, and also disables 3rd party extensions that may cause problems.

Start up your Mac in safe mode - Apple Support

If that does not correct the issue, test in a new user account. A newly-created user account will have all settings at default, and if the issue does not occur in that new account then it provides guidance on what may need to be changed to correct the issue.

Add a user or group on Mac - Apple Support

Once the testing is complete, the new account can easily be deleted.

Delete a user or group on Mac – Apple Support

Those steps will help to isolate the problem.

It might help to download and run EtreCheck, written by a long-time forum member. The free version is fine. Post the full report using the Additional Text button. No personal information is revealed. 

Personally, I have a 16" M4 Pro MacBook Pro running macOS 27 Golden Gate. I just put my Mac to sleep then waited a couple of minutes, and after pressing a key it took about 1 second or a little less to unlock with my Apple Watch and fully wake up.

Setup:- M1 iMac, MacOS 27.0.1, Older Dell monitor in portrait mode (U2412M), via HDMI.

I tried booting in safe mode, but the problem continued. Now reboot to normal.

Now switch Dell monitor off, same apps loaded. Problem gone. So I guess the driver for the Dell monitor is showing its age?

With the Dell on, and waking from sleep, waking from sleep shows windows related processes >50 % CPU. No spinning beachball if I wake before the Dell goes into energy saving mode.

Not the end of the world. I'll put up with it now, knowing when the problem happens.

I have just checked my M4 mini using Tahoe and it takes around 10 seconds.