How about this to enhance on-time performance?
Stop making flight crews change airplanes every bloody time they go through a hub.
Every time you schedule an aircraft change -- or worse, when there's an unscheduled change for no apparent reason -- you just upped the odds of making at least two flights late.
And if it's absolutely necessary to change planes (like from a 320 to a 321, or a non-EOW to an EOW), how about looking a little more carefully as to where the inbound and outbound planes are parking? I cannot count the times recently that a crew has come in on C-29 in PHL, only to be scheduled to depart from A-19, 45 minutes later.
A couple of months ago, the very same scheduled trip each week had a crew come into B-16 in CLT, and depart from D-7. Every single time. And the outbound flight departed late. Every single time.
I can assure you that when a crew has to clean the cabin, then trek a mile-and-a-half to another gate, only to encounter an agent with the "Where the hell have you been? I want to board this flight and go on break" look in their eyes, that flight will not depart on time.
And if it's an unscheduled change, that just so happens to coincide with the one between-flight break upon which the crew was planning on eating or putting in their bids, I would encourage the crew to go ahead and do as they had planned. We didn't schedule the aircraft swap between the end of C-Con and the end of A-West.
The flight will depart when we're damn well ready to depart.