Like Joe says above you cannot expect the machine to go as fast around a corner as it could going straight. That said, there should be settings in the control software to adjust this to real world conditions. I.E., if set at 100 ipm you should easily be able to maintain that speed on a radius of a certain size. That size varies with the overall speed, but none the less, there are settings in the control software for user testing and adjustments.
Some higher end controls actually use an algorithm that factors in centrifugal force and have a single number that allows for easy adjustment. Think of this as a weight suspended on a string from a cars rear view mirror. From straight down (zero force) to straight out to the side (max force) as a scale of numbers. This allows the number to be adjusted to the machines capabilities (mass, rigidity) and then perform close to those abilities on speeds fast and slow on arcs or curves of small or large radii. This allows for speed without loss of quality or accuracy.
Find out what is available for your control, do your homework and test away!
CNC Technology & Training
The Ultimate Woodworking Machine
GCnC411 (at) gmail.com