Is it normal that the defragmentation of a hard drive (C) takes about 4 hours and is still not finished?

Windows 8 laptop approx. 800GB storage space

Is there anything else moving? So if nothing has happened in a while he has hung himself. Otherwise just wait until it's done.

I assume that with Win8 NTFS is used as the file system and then a defragmentation is nonsense, that comes from the FAT times, there it made sense

Ne it is still running> it says "Successful step 8 - 36% consolidated)

With an 800 HDD platter, it takes a while if it has not been cleaned up for a long time.

And what should I do now?

This can easily take 24 hours or even longer.

Let it go through or interrupt it.

Your decision

The less free space there's, the longer all the fun will take because the smaller the datasets that can be moved.

800GB is also a house number, after all, reading and writing take place here on the same hard drive.