Spooler SubSystem App is a Windows component used by Microsoft Office applications such as Word, Excel, PowerPoint, and Outlook. This application is responsible for managing print jobs sent to printers attached to computers running Windows operating systems. Spooler SubSystem app runs automatically each time you start one of those programs.
The problem occurs when the system becomes infected by malicious software. When it happens, the spoolsv process uses up too much memory. In some cases, the process crashes and causes errors.