There are many programs that purport to clean up and optimize system performance. While Microsoft does not endorse the use of these tools with Windows, we do not view them as unwanted or malicious.
Many programs in this category have a practice of providing a free version of their software that scans your system, presents the number of errors it found, and offers you to purchase the full version to remove these errors.
However, some programs run on your system and display only an aggregated sum number of errors, without disclosing to you what the errors are, which items they stem from, and what benefit will you get as a result of correcting them. This lack of disclosure deprives you of the clarity and transparency you need to determine the validity of what is being called out as errors, and of the value you can expect from the action the program is proposing to be taken.
This becomes even more accentuated when a free version of a program calls out errors and warnings, doesn’t provide you with any clarity as to what is wrong, and offers you to buy a premium version in order to fix the errors the free version found on your machine - albeit not letting you know with clear specificity what value you can expect from the purchase of the premium version of the program. This makes your purchasing decision arbitrary, and fear-based, rather than rational.
Another example of an unwanted behavior is when system cleaner/optimizer programs present Windows-created prefetch files (.pf) as errors, or encourage you to remove them. Prefetch files are created by the Windows operating system to improve its performance by reducing the load times of programs. They are not errors (or ‘junk’ as some cleaner/optimizer programs refer to them). Such programs should neither mislead you to think these are errors or junk files, nor should they encourage you to remove these operating system created files from your system.
Our criteria states that you must be able to expect that the actions a system maintenance or optimization program takes towards system performance are actually beneficial. Unwanted behaviors include displaying exaggerated claims about the system's health.
Accordingly, to be compliant with our objective criteria, programs must provide details that back up their claims, so that you have the ability to assess what the program found and deems to be errors, and determine if you’d like to take the program’s recommended actions.
Microsoft security products, such as Windows Defender for Windows 10, will continue to classify optimization programs that do not provide details as unwanted software, detect and remove them.