I don’t actually like the phrase ‘optimizer’, as the result of using such programs seldom can be measured. That being said, I’ve never had problems after running Glary Utilities.
Glary Utilities comes in both a free and a paid version (Glary Utilities Pro).
It does much of the same as CCleaner: Removing unused files and registry entries. In addition, Glary Utilities has several modules, like File Undelete, Duplicate Files Finder and Process Manager. Click to see a table of modules.
The program has a good rating at Download.com from both editor and users.
I recommend the Slim version, as it comes without the Ask toolbar. A portable version is also available. Both can be downloaded from the ‘Other builds‘ section at glaryutilities.com.