Yes, the HDUI is a bit sluggish at times and I know the hiccup with the preview window, it's just how it is I guess. Ideally, there would be a better processor to handle the HDUI better, but it's really not that bad, IMHO.
As for managing future conflicts, the SPM and To Do lists were just recently updated to HD and added some new features that should hopefully make conflict checks like you're talking about much quicker. See the following link here.
You can either sort the To Do list with the "c" button to get it to show conflicts only, or you can run through your SPM and look for (conflicts) towards the right side of the list.