Setting Player Velocity to the same on X and Z makes movement slow

Hi! I am basically trying to create a zero gravity environment and ran into a problem. First I tried doing this to set the Y velocity
p.getVelocity().setY(flystr.get(p));
Flystr is the hashmap that contains the player strength of flight
That did nothing.
Next which is what is the problem is I did this:
p.setVelocity(new Vector(p.getVelocity().getX(), flystr.get(p), p.getVelocity().getZ()));
as you can see, I am setting the player x and z velocities to whatever it was before.
But this makes a wierd slow sluggish movement that I don't like.
How would I get rid of this?
Thanks!

 

I doubt you can: everytime you change the velocity of a player on the server, the client gets slightly 'set back' / interrupted in its current movement, because the client is expecting a different movement than you force on the server slightly afterwards.