Rundll, as its name implies, is a program that runs a dll, or a program that loads a dll, because dll files on windows, referred to as dynamic link library files, contain a lot of codes that need to be executed by programs, and sometimes rundll32.exe files are needed to load them, because dll files themselves cannot be run. Generally speaking, it is normal to have multiple such processes.

The solution to high cpu usage is:

One reason for occupying CPU may be P2P sharing service for background update. You can choose to turn off P2P sharing. Method: Open System Settings-Update and Security-Windows Update-Advanced Options-Choose how to provide updates, just turn off "Update in Multiple Locations".

2. If you are using Win 10 Home Edition system, and the Windows Spotlight function is turned on, it may be that the background service of this function leads to high CPU utilization. Open the system settings-personalization-screen lock interface and select other background modes.

3.Windows prompt function may also lead to high CPU utilization. This function will push some notifications about system functions and characteristics according to the user's operating habits. If you are already familiar with Win 10, you can turn it off. Open System Settings-System-Notifications and Operations, and close "Show Tips about Windows".

4. After deep acceleration with 360 security guards or Tencent Butler, slim down the system disk.