When you uninstall software on Windows, the uninstaller doesn’t necessarily remove everything from your computer. While you can employ the CCleaner utility to remove software completely, historical uninstalls and other problems will have caused issues with your Windows Registry.
The Windows Registry is like a vast database of filepaths and instructions for the operating system and installed software, and it can become corrupted and overloaded. These issues will cause slow boots, poor performance and a very slow shut down, as well as an inability to resume from sleep/standby modes
Once again, CCleaner can be employed here, but there are many other tools that can be used to fix problems in the Windows Registry. Remember to back up the registry before running tools that might cause problems, even if your PC is running slow