Slow opening PDF files

Dears,
I have noticed for the last 14 days or so that PDF files open very slowly on my computer, so that if I click twice on a file that is saved on OneDrive, it opens in about 15-20 seconds.
The problem is the same when the file is placed on the desktop or anywhere else.
I don't have this problem on another PC.
What could it be, how can I fix this problem? This is a very annoying issue when dealing with a PC in an office where PDF files are worked with constantly and over and over again on a daily basis.
Thank you.