Slow opening file that has a lot of edits/layers

I guess it's seemingly known that On1 is not the fastest photo editor around.  I moved over from editing on my laptop (no graphics card) to a PC desktop that exceeds the technical specs for On1 2019.

That said, editing a new raw file is reasonably fast.  BUT... I've found that when my editing is done, and gosh forbid I try to open the edited file again, and then push edit.... it can take 5 minutes or longer until the file is ready for edit again. 

Is there a technique to re-opening large edited files that I'm not doing correctly?  I wish to be able to continue editing, so I don't want to flatten the file.  Any suggestions as a workflow for this?  Or is this another thing that On1 tech support is working on?