DAL,
I think it's fair to say that in general, Computer Aided Design and computational fluid dynamics have aided in reducing the drag of modern aircraft to a far lower level than earlier jet aircraft. Therefore, it might seem reasonable to assume that less of the thrust produced is required to overcome drag, and more is available for other purposes. However, it's a complicated field which most aircrew touch on briefly and never fully explore. Suffice to say that the tefal-heads work out the handling limitations of the jet and you stick by them!
However, it is worth remembering that the stores hanging from the aircraft in question will also have a flight envelope of their own to be adhered to, and this might be the limiting factor in how fast you can go!
Blunty.