@Eggbert,
The best advice I can pass along to you is the following:
Unless you’re an expert at cleaning the registry, leave it alone.
“If it ain’t broke, don’t fix it.”
The time saved by cleaning and/or defragging your registry is minimal at best.
One wrong entry or one removal of an entry in the registry can lead to much dismay and,
can leave your system unbootable.
Your computer, your choice. 