Vmo reduction below 5000ft
I was always under the impression this was the equivalent of the 'bird speed' limitation some older Boeings carry.
We would definitiely have performed better if we could have got to 400kts at, say 3000'.
Interestingly, this was a fairly blunt instrumenet insofar as it was based on pressure altitude, so departing from Nairobi (where there's a good chance of meeting sizable birds) one would find the barber's pole already at 400kts or so.