You could create a simple filter, search for date prior to a specific date, and move to a new folder. Then, review the folder for any unintended messages to move back, and then empty the folder. Or, if you're confident of the search, have the action message send them all to trash.

To add to david's ideas

1. if you are deleting by age/periods - a fast method is select the oldest message you want to delete, scroll past say a 1,000 messages to a "newer" message, hold the shift key, right click the mouse to select 1,000 messages. Then hold the shift key and hit delete - this will bypass moving these to the trash folder. 2. You can use the quickfilter button to then display messages by subject or email address, and then further refine the list using #1 above.

Thanks for help. Deleting messages ok. Not sure that is the cause of slow running.