Slow Booting Time with FastBoot enables - slowish performances

OK, that's a big update, for sure :)

Effectively you will be doing an in-place upgrade so it will find new drivers and basically create a new windows directory leaving your old one in a separate folder called windows.old. It will copy over your old profile though so if there was anything wrong with it, it could carry over into your new version. If so you may need to go through the procedure of creating a new account again.

Also note that for the first few start ups on the new Creators update the boot timings will be longer as the new system sorts itself out with background processes.

So, so far it seems to work now:

Power to password: ~10sec
Password to desktop: ~10sec
Then once on the desktop, the disk is at 100% for a few seconds, then it's fine.

So it seems like I had been a bit off on the updates. I am and was on automated updates, but I guess if some files were corrupted that messed the whole thing.

I'll work out if I can enable back some programs at start-up, but otherwise thanks for the support! I'll live the thread open if I get other issues related, otherwhise I'll mark as solved soon.

Good plan, glad it seems to be sorted :)

The only tool able to help you is Windows Performance ToolKit.

Slow Login For Domain Accounts After Creator Update (1703) : Windows10

if you need some help taking and analyzing your boot trace, let me know. I'll be glad to help you.