Sticky Notes Lag Issue

Not sure what's going on, but we're experience a severe performance issue with Sticky Notes in Acrobat Pro on our Mac's.  Seems to be isolated to High Sierra, although I'm not 100% certain.  When a user tries to add a sticky note to a PDF, it takes a very long time.  The little round thingy just spins and spins for about a minute, before the note field is added so the user can enter a note.  Just clicking on the comment tool takes a seriously long time.  This is when working on the local network or a local PDF.  Size of the file doesn't seem to be a big factor, but performance does improve with smaller files.  Still, my PC has 0 lag.  I click and it goes immediately.         

They are older 27" iMac's (2010), which are maxed out at High Sierra.  Performance is still decent on these machines.  Put SSD's in them a few years ago, and recently upgraded those again.  I think we're running 12GB of ram.     

Anyone experience anything like this?