Bill just updated to Windows 10 vs. 2004, and now it takes a long time to boot up. Leo says that it seems to be a known issue with this update. Microsoft has a terrible track record with sufficiently testing updates in beta before it's released. But it could be some software is challenging the system and slowing it down. You could run the system file checker or the online cleanup option to see if it helps. Also, look in your device manager to see if there's any yellow "!" or red "x". Something may have broken. Leo also recommends updating firmware and drivers.
He also says that his wife's profile boots the computer up faster. Leo says that's an interesting wrinkle. It could be that there's something unique to Bill's profile that is placed on a bad sector. So Windows is slowing down while it's trying to read it. Leo recommends creating a new profile and move things over. It could also be fonts. See if that helps. You can also use SpinRite on it. But at $80-90, that's an expensive option for a one-time thing.
You can also download AUTORUNS from Microsoft. It'll tell you what you're running that she isn't.