The CRJ's normally cruise between .74 and .77. The 200 series can make .80 much of the time if you want to burn lots of gas. They do require a fair bit of runway if there's contamination due to no leading edge devices.
The 700 series will go straight to FL410 and can make .80 cruise at most altitudes--but most people don't do that because the time saving on a 1hr leg will not be offset by the extra fuel burn. It also uses much less runway because it has slats.
As for the "reputation" of going slow, this likely comes from that "RJ" that is powered by four APU's.
From what I hear, they barely keep up with some of the new turboprops.
