In a large >700 folder location, where the automatic file size calculation is used, i have to wait, until the calculation finished for all folders. Attemps to enter a folder, or to move the focus, will be postponed until the calculation is done, as it seems. I also have a file count column, but removing that didn't have much effect, whereas turning the size calculation off bring things back to normal.
Please forget the whole post. Something completely embarrassing happened to me. Some issues i had reported where obsolete. I accidently installed 12.05, which was flying around here among a list of betas. Since i quit Opus when i want to install a new version, using Explorer, i must have mixed up 12.15, which was lower in the list, with 12.05, which also explains my worries about the tab colors, recently. With the current version it's exactly how i prefer it. Sorry! 
