I can live with a 280kt. climb, get to cruise alt. faster and be on my way, I just don't know why (at the world's busiest airport) they haven't specified a common climb speed for all departing jet traffic, so we can maintain our separation and get out of there as fast as possible.

Seems when ever we slow to 280 we are next told to level off at 230, and wait....wait....wait...for the RJ's in front to climb all the way up to...290, and get some spacing, before we can continue on our way.

Why not hold the RJ's down to 250 or below and let the big dogs eat? The Heavies have 8-15hr. legs to go, and spending the first 10minutes held down at fl 230, at 280kts, is not helping save any fuel.