First off, the CV wizard is really intended to control CV based off of angles. It is mainly only needed for 2.5D work on machines that are about as rigid as a wet noodle and the programmer is too lazy for program realistic speeds for it.
If you are doing 3D work or very granular G code, then you probably do not need the CV wizard at all. Blow the CV section out of the Machine.ini of the profile or create another profile and don't run the CV wizard.
Next, CV is really a misnomer, IMHO. It is really VB (Velocity Blending). Thus CV is wholly dependent on your motor acceleration parameters. The higher the acceleration parameters you can use, the better CV will hold to the actual path. So run your accel parameters up until the steppers start screaming and losing steps and then back it down. It may just have really soft acceleration parameters even though it was professionally configured.
And also check your look ahead buffer. Pop it up to 200 or so from the default 20 and see if that helps.
For me, my 3D profiling stuff is silky smooth. But I'm using a Mach4/Galil with analog DC servos that have torque that allows for insane acceleration parameters. And it absolutely chews through very granular G code.
Steve