It is necessary to know the bare minimum processes which Windows needs to operate, and it is sometimes difficult to tell.
Here is a list of the essential processes that Windows needs to run correctly.
System Idle Process
svchost.exe – You will notice more than one running.
By shutting down anything other than these processes, stand alone Windows should operate fine, however, if any of these processes are shutdown, Windows will start to become unstable, or unusable.
On most computers there will be multiple instances of svchost.exe, these control various connections on your computer whether it is to the Internet, or within a LAN. It is usually safe to switch off some of these, however, it’s not easy to determine which ones, so its better to leave these alone.
To shutdown a Windows process, Press Ctrl+Alt+Delete which will take you to Windows Task Manager, click on the Processes Tab, select a process and click End Process.
If you are not sure what a particular process does, then I recommend checking out Uniblue Process Library, a library that lists what each task does, its threat level,and makes it easy to determine what is running on your computer.