I agree with Ferris, but I also would like to say, that the term "high speed" must be one of the most wishy washy terms used here. One pilots interpretation of high speed is different to anothers. Personall I like to ask what speed on descent a pilot can maintain, and set it at that. Otherwise you tell a guy high speed and it turns out he has decided that 290 kts. is high enough for today, and conversely, another guy squeezes 340kts out of his machine when asked for high speed. Its a bit like asking a pilot to give you a good rate of climb. An Air France 742 thinks he is giving you a good rate of climb if he gives you 500 ft a minute, while an MD11 will give you 3,000ft a minute. Personally I try and nail down what everyone is doing so everyone is on the same page, and then if any of the pilots can't hold up their end of the agreement, they speak up so the plan can be tweaked.
Just an aside, if you are on departure, and you experience turbulence (and you are a Gulf Air A330, not to name names at all), and you pull back to 260kts, with a company aircraft clearly on your TCAS 11 NM behind also climbing, would you please say something to ATC about reducing your speed dramatically. It certainly changes the colour of the ATC chairs when the following company traffic doesnn't experience said turbulence, and continues on at 320kts, and all of a sudden you have 100kts ground speed closing. Even without anyone on TCAS, if you pull back by 50 or 60 kts indicated, please tell us. We are very interested in these things, believe me!