To improve the performance of a slow computer, the first step is to restart the computer, close unnecessary applications, check applications that load during startup, and close applications that are not necessary. The computer should also be cleared of temporary files, applications that are not necessary, and malware through antivirus software. The operating system should be updated, especially if the computer is running the Microsoft Windows operating system. In addition, the computer may benefit from additional RAM or an SSD drive, replacing the hard drive, which improves the performance of the computer significantly.