The problem is most likely an application that does not match the new requirements of High Sierra 10.13. Does not matter if you have installed 10.13 or the update 10.13.1. The problem will not be solved, just because that is not the real problem. Several things are already mentioned, but I will summarize the best methods to tackle the problem with an explanation why you have to do them. Check your filesystem.
1. Check your filesystem for errors.
Boot is safe mode (Re-start while holding Cmd-R), Choose for the DiskUtil and run First-Aid over the Partition and the HardDisk. In case of error repair them. Obvious filesystem errors are a killer and may cause freezing of the OS.
2. Check your system using a new clean user.
Isolate the problem by creating a new user, log-out and and re-login as this new User.
A new user us clean and uses the bare system. If you have a freeze using this new user, the problem has to do something with the new High Sierra update. Contact Apple, keep the new user for reference and the optional sending of the system.log.
If the freeze does not happen immediate, most likely the problem has to do with some applications you are using.
3. Start with your own account without any Apps loaded at Startup.
Login with your own credentials and go to System Preferences -> Users & Groups. Choose the tab 'Login Items' and remove all items that are listed there (write them down so you can re-enter them later). Restart and login with your own credentials. Now test your system. First do nothing and see if you get a freeze. If not try an app, test it for a freeze. Most likely you don't have any or you get one using a specific app. At that time you know the problem.
4. Re-enter the login items.
If your system is still stable after performing all the steps above, you can try to re-enter the login items (System Prefs -> Users & Groups).
I hope this will help to track down the real problem.
I have found several apps that cause problems (my list is very limited because I am still testing). Please note the apps below does not necessarily cause a freeze.
- MySqlWorkbench, the latest versions will not, try version 6.1 instead.
- Microsoft Office, Excel decimal point settings are not recognized anymore.
I did not have time yet to test the possible freeze, because I need to finish another task and can not have a freeze now. When I have time I will update with a list of freeze-causing-apps.
For now my uptime is :
$ uptime
12:05
up 2 days, 19:09, 5 users, load averages: 1.35 1.00 0.88