Hope you are doing well and sorry for the trouble. As described the application is running slow.
- Is this a behavior with a particular PF file or with all the PDFs? Please try with a different PDF file and check.
- What is the version of the Adobe Acrobat DC you are using? to check the version go to Help > About Acrobat and make sure you have the latest version 21.01.20145 installed. Go to Help > Check for Updates and reboot the computer once.
- Are you on a work network/device? please try to switch to a personal network/device and see if that helps.
- If the file is stored on a shared network/drive please download it to your computer first and then try to open it with Adobe Acrobat and check.