PDF taking a long time to open up as an outlook attachment

Threre have been numerous post about pdf's taking extrmely long time to open when they are an outlook attachment but i have not found any true fixes. If anybody has any ideas I could really use them right about now. This is affecting all my users, we have different Acrobat XI, Acrobat DC and some that just have Adobe Acrobat Reader. I just started happening 2 days ago, but there hasn't been any fix. I can't see uninstalling and reinstalling the program if it is affecting everyone. It would be different if it was a couple users. Also, If I open Acrobat and leave one document open then all other email attachments open quick and fine. I have checked to see if there are any Adobe updates, Microsoft updates and Windows updates and there are none. I contacted Adobe support and they said they don't what would cause it they had me change the default application to edge and it opend fine. Thank you, Will