As Graham siad - Is this a curve - i.e. a G2 or a G3 generated by the G Code, or is it in fact very many straight lines just joined together to look like a curve.

The first is easy to produce since the two axis accelerate/decelerate at a predertermined rate together and the whole move can be computed at one time.

The second one is different, and whether you like it or not, the machine has to stop between each move, pick up the new information for the next straight line, then accelerate away again. Since the angles on the curve are different, the rates of movement of each axis, in relation to each other are different for every move. If some of your lines are millimeters long, this takes time. The CV mode cheats in that it picks up the next move and as axis slow to a stop from the previous move, they accelerates again up to speed for the next one - the overlap can be set.

I don't know what is writing your G Code - but it may be quicker if, instead of straight lines, you did away with say half of them, and used G2 or G3 to join up the curves - that, however is quick complicated.