Hope you are doing well and sorry for the trouble. As described the after opening PDF, the CPU usage increases and it loads very slowly.
Would you mind sharing the version of the Adobe Acrobat Reader you are using? To check the version goto Help > About Acrobat and make sure you have the latest version installed. Go to Help > Check for Updates and reboot the computer once.
Also go to Edit > Preferences > Page Display > Under Rendering, Uncheck 'Use page Cache' > Click OK and check if that makes any difference.
If it still doesn't work, please create a new test user profile in Windows with full admin rights and try using the application there and check.