sandro c wrote:
I do not know if there are tools that can test the performance of windows system , or if after 10 months of various installations and uninstallations , the system is polluted and installation should start over with a "virgin" .
Depending on what exactly you install and uninstall, an operating system can get cluttered with junk. Something the majority of people do not know for example is that the majority of uninstallers out there do a really mediocre job at entirely removing an application.
The registry can get cluttered a lot by leftover entries, programs leave shared components installed that are unused, other uninstallers leave services running (notice that not all running services appear in the "Services" MMC snapin--a lot of those, specifically driver related, can only be seen in the registry), SxS folder slowly gets bloated as you install software that require different versions of libraries (Windows 8.1 has finally a nice feature that cleans this particular folder over time), etc etc.
While it is possible to keep a windows installation in a top notch performing condition, unfortunately there is no automated tool for this job. It takes knowledge and time to do it manually. Personally, I spend an hour monthly doing maintenance, cleaning everything that needs cleaning by hand. Tools such as registry cleaners etc are entirely useless. They can be used as a way to do certain things faster but it implies that you're actually know what you're doing. Blindingly using registry cleaners CAN and WILL cause you trouble because they rely on heuristics in order to figure out what's wrong and how to correct it. Much like an Antivirus can give you a false positive, a registry cleaner is far more prone to do the same for a particular registry entry, or even worse fix it in a way that it should not.
As a fairly standard example, a registry cleaner may detect an empty software registry key and put it up for deletion without knowing that this key is actually being used by the application in order to figure out if it's running in installed or portable mode.
My personal advice is to refresh the OS every now and then and avoid unnecessary installation of software. If you want to test something to see if it's something that you actually want to use, use a virtual machine to do it. VMWare Workstation or VirtualBox, which is free, are good solutions for this.