NerdFencer

I looked into VLC, and it appears that there aren't any superfluous files or registry keys for CCleaner to remove.

It would be quite nice if there was a Silent/Quiet Uninstall option in the Uninstaller Tool The REG_SZ value "QuietUninstallString" in the "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" uninstaller references is an optional value for executing a silent uninstall of the program. This can be used where available. The "/quiet" switch can be used for the MSI uninstallers. Although this is not available for all uninstallers, it would be quite nice to have for those where it is.

Cleaning Slack space would (in any conventional way of cleaning it) entail moving every file on your hard drive, which could not be doe for all items while your system is running, and to do it right would require a boot-disk. This is not a practical request for this type of utility.

Contrary to popular belief, Prefetch is there for a reason. The entre idea of prefetch is to pre-load components for programs that you use often to speed up their launch. Prefetch does not contain any "vital" components for running programs, but is actually just an optimization that microsoft built into the operating system. Deleting the prefetch data has a SLIGHTLY positive effect on boot time, but slows down the launch of your commonly used programs. Deleting all prefetch data does more harm than good, although microsoft does say that it can sometimes have a slightly detrimental effect on EWF performance, but this is not a consideration for almost any PC users. The space that you (temporarily) save is insignificant, but the decrease in performance is noticeable. I just ran some program opening benchmarks on my laptop, which measured the opening (time from execution start to window appearing) speed for three of my programs (twice per program), deleted all prefetch data, rebooted, and ran again. The Result was an average of a 19.627% drop in program opening speed. Although I admit I did not do this in a perfectly controlled environment (such as a fresh virtual machine), this is a significant enough change for me to say that deleting all prefetch data is a mistake. If you still believe that prefetch is a waste of space, you can disable it by following Microsoft's instructions here.

Could a clean registry option be added to to the command line options like /AUTOREG or something?

This could also be done with a /RESTART argument that could be used instead of /SHUTDOWN. If doing this, to make it complete, some users may also like a /STANDBY argument (as some users don't like to wait for the full boot time). This would be optimal because all the options would be available to the people who want it automated. Of course, this would eliminate one advantage of the menu, that being the real-time selection. This advantage could be better leveraged with a custom menu for a /SDPROMPT option that would allow you to select which option before it runs so that you can then just walk away, giving you the advantages of both options (although slightly more time-consuming to implement). Honestly though, I see little need for the real-time selection if the options are available by command line, the only exception being a computer savvy person setting up a batch file to do it for a not-so savvy person. Call me a feature creep, but I also see why a user may also want the option of logging off, or switching users. This could be added to the custom menu or command line parameters easily, but not to the windows default Shutdown dialog. None of these options should be difficult to implement, but I do think that the additional shutdown options would be a useful addition to the utility.

Download the portable build and use that instead.

If a registry key references a broken key, or that key references a broken/missing key it is not detected. Those keys are later removed by CCleaner, making it possible for further errors to be detected in the next pass.

I'm not an expert, but here is the gist of it... Unused File Extension These are references in the registry for how to deal with file extensions. When CCleaner determines that it is "unused" it means that it references software that no longer is on your computer, or registry keys that no longer exist. Missing Shared DLL Shared DLLs are libraries used by windows programs. When a Shared DLL is missing, the file for that library no longer exists, but is referenced in the registry. Uninstaller Reference Issue Installer Reference Issue These are references in the registry to uninstallers to run when trying to uninstall that program. When this type of problem is detected, that uninstaller no longer exists. ActiveX/COM Issue ActiveX, a component object model (COM) developed by Microsoft, runs in Windows environments. I do not know what Kind of issues that CCleaner fixes with this. Old Start Menu key Just what it sounds like. Invalid Default Icon Just what it sounds like. Missing TypeLib Reference The TypeLib table contains the information that needs to be placed in the registry registration of type libraries. CCleaner removes references to non-existent type libraries. Open with Application Issue The default application for opening a file type is missing. CCleaner deletes these references. Application Paths Issue The application path points to files that do not exist. These references are removed. Missing MUI Reference The Windows Multilanguage User Interface (MUI) allows windows to function in multiple languages. I do not know what CCleaner does with these, but it's pretty safe to say that it probably removes references to some sort of missing components or files. Obsolete software key These are left behind by removed software, and are simply deleted. Help File Issue Probably references to missing help files.... Invalid or empty file class These are file extension entries that are broken in some way, and are simply deleted. Missing Startup Software Software that is slated to start up during boot up or log on is missing. I hope this is helpful

From what I understand (and I am not really an expert so don't bash me if I get something wrong here), Registry "Defragmenting" otherwise known as Registry "Compacting" differs a lot from traditional Registry Cleaning. In registry cleaning, unneeded or unwanted registry entries are removed, this leaves "gaps" in the registry so that the computer does not have to re-write most of, or all of the registry back to the disk without that space. Similarly, when values are written to the registry where there is no blank area, they are appended to the end, resulting in the "fragmentation" of information. When defragmenting or compacting the registry, these spaces are removed and entries placed in their proper locations. This can result in both a decrease in space used by the registry, and a performance increase for registry operations. I cannot give an estimate for the performance gain, but I can for the for the lessening of space used by the registry. On my computer, I reduced the size of the registry by 7% by compacting my registry. (I used 3 tools in verifying this because I was skeptical) To me, this seems like a useful and reasonable addition to CCleaner.

This is also true with registry keys, software often leave empty keys in HKEY_CURRENT_USER\software

The Registry Scanner misses deleting file extensions in HKEY_CLASSES_ROOT that reference missing reg keys in their default value, which is supposed to contain a valid name for another key in HKEY_CLASSES_ROOT.

When Running Scans in CCleaner v2.17.853, certain invalid Application paths are missed. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths -Each key at this location contains a value for the location of the corresponding application. -No (as far as I can tell) invalid application paths are detected here

I have gathered the locations of a few more files that should be deleted by CCleaner... -Log Files Here are some more Log Files that can be deleted... WINDOWS\Sti_Trace.log WINDOWS\wiadebug.log WINDOWS\wiaservc.log WINDOWS\WindowsUpdate.log -OOBE The OOBE Directory is the place that Windows stores all the crud that you see when you booted Windows for the first time. This can be cleared out after the initial computer setup is done. WINDOWS\system32\oobe\ -Windows Temp This is just another temp directory. WINDOWS\Temp\ I hope this information is of use.

From what I have gathered, CCleaner checks HKCU\Software\Microsoft\Windows\CurrentVersion\Run and HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run as well as the user Startup directories for the Startup Tool The following locations contain single programs that are also executed during logon... HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Userinit HKLM\System\CurrentControlSet\Control\Terminal Server\Wds\rdpwd\StartupPrograms These are slightly more system critical entries, so if they are added, they should only appear if an advanced option for them is checked.