Scrivener freezes

I have had a few occasions when Scrivener has frozen - this always happens in the same project, which happens to have a number of PDF files in the Research folder. Typically this happens when I am going from one folder to another. This happens sporadically.

… I guess my question is whether people have experienced “freezing” problems like this, whether it is problematic to keep a lot of PDF files in the projects…

I have had occasions when it has slowed down while loading a bi-i-i-g PDF (i.e. one where they’d not had the sense to streamline the file in Acrobat). The first couple of times I jumped the gun and force-quit Scrivener. Subsequently I just waited for a while and it did its stuff in due course.