Well, now it is hard to tell if some upgrade was done you may not know about, so you can't really rule that possibility out.
Do you ever allow you laptop to sleep? Mine goes to sleep when I shut the lid and hibernates several hours later.
There is quite a difference between shutdown and hibernate. Since Hibernate writes everything in memory to the drive, maybe something is not behaving well. A shutdown does not do this step so should shut down a little quicker. But if it is delaying during startup or shutdown, it is probably waiting for some scan, or being required to check something, or some utility is not allowing a quick shutdown.
So the first thing I would recommend is to check your system files. Open an administrative command prompt and type
SFC /scannow
and allow it to finish. Let us know if states it cannot repair some files.
Also, the Powercfg utility is used to check for power configurations. In the Admin command prompt, type
powercfg -energy
and let it finish. Prior to doing this, shutdown all non-essential programs. When it is finished, copy the html report to the desktop and open. There are usually USB error messages, but let us know if any devices or utilities are indicated as being suspicious.