There is no such thing.
You can run CCleaner. You can run Registry Repair. You can run Registry Crawler. There is no such things as optimizing your Regitry. That is a illusion.
The Registry is always cluttered with things left over from unisntalls, installsm=, and everything else. The best thing you can do is use Revo Uninstaller when you unisntall something and remove the Registry entries.
Other than that get Registry Crawler and search for applicaitons you have already removed and delete those entries.
Careful as some may still be in use and cause a fatal system crash.