I don’t know if its a bug or not, but if it happens on PureRaw2 and it didn’t before, maybe it has to do with your hard drive, either hardware or software issue. Alternatively, maybe some program running in the background and scanning, like antivirus could be an issue. I’m on PC not MAC so I can’t test it , but maybe someone who is using MAC will know more. Also do you have any new other software installed since the issue started happening? Or it was only DXO?
Do you get this delay while using DPR as a standalone application?
If yes, I propose that you get in touch with support.dxo.com (look near the end of the webpage for details on how to do it) and provide as much detail about how you use the app, where you have your image files, version numbers etc.
If no, we’d need more details on what you do exactly…and all the details - as in 1.