PDF's slow to open says 'Verifying all signatures'

I have a document with multiple signatures.  When opening one of the documents that have been saved and the signatures applied there is a message that says'Verifying all signatures'.  The digital signatures are self signed and not provided through one of the certificate vendors on the Adobe Approved Trusted List.  I am wondering if the reason it is slow to open and why I am getting the 'Verifying all signatures' message is linked with that?  If not, are there any recommendations on how I can solve the issue?