I've mentioned this before, but I'm glad to see we finally did this... I don't know who landed this fix, but I'm glad it landed.
Here's the old vs. current behavior for multiple selection (that I used to time Batch Delete Speed). OLD: When you multiple select outliner items, we would always display the 1st selected item in the list in the Message Pane. CURRENT: Now when we multiple select outliner items, we don't display any message contents in the Message Pane. How this helps perf: On batch deletion, we would always have to clear the Message Pane contents. Now, our batch delete looks much faster since we're not doing this. See the data below (all in seconds, time to batch delete 5 messages from a Local Folder): 1-10 build: 0.86 (0.85 0.85 0.87) 1-18 build: 0.68 (0.67 0.70 0.67) Whoever fixed this, thanks! (Jan Varga, Navin Gupta and David Bienvenu are my likely guesses) - Stephen
