I believe this sluggish you are referring to is still a GUI issue rather than it being quantizing related. Slicing multiple audio files, especially a bunch of drums edits is still causing sluggishness.
Look for my post with the (Drums_edits.png) attachment. You’ll see that I also encountered this issue.
The only thing that can help as a workaround is to put your events into parts, this way you can avoid having to bounce your edits/slices.