According to their catalog,the Vtec is 5 fps slower(305 fps) than the Xtec(310)
I believe the only bow to actually pick up speed is the Protec.They redesigned the riser so it has a little reflex to it while the grip is still deflex along with making the A-A a 1/2" shorter.
If all goes well,I will be ordering my new Protec tomorrow.

I plan on getting a pretty one this go round with spirals.[:-]