Q: PDF files keep freezing

Hello csnappremax

I understand that you are having issues with Preview crashing on your when trying to view PDF's. Let's see if we can figure out what is going on. 

The main thing to figure out is if this is happening in just your user or system wide. Try creating a new user on you Mac to see if the issue appears again. You might also want to see if it is always one PDF or just all PDF's. take a look at the article below for more details. 

How to test an issue in another user account on your Mac
https://support.apple.com/en-us/HT204443

Mac OS X: How to troubleshoot a software issue
https://support.apple.com/en-us/HT201516​

Let me know if this works. If it doesn't, let me know what version of OS X you are using so I can try to find something that may take care of this for you. 

Find the OS X version and build number on your Mac
https://support.apple.com/en-us/HT201260

Take care