I've had this rather annoying issue since I first upgraded to Windows 10 (not via upgrade, but fresh install).
Whenever W10 opens the Open or Save dialog (i.e. you press Ctrl + S or Ctrl + O in most programs), about 8/10 times the dialog box will freeze for about 5-10 seconds before allowing you to do anything.
Has anybody else had this issue, and does anybody else know how to fix it? Thanks!