Noisy serpentine belt / tooth-belt

Hello!

Just finished my DIY CNC mill project and finally started to make some chips, but its alot of noise from the tooth-belt that drives the spindle, specially under heavy loads.

My belt is 720-S5M profile, 30mm wide, it came together with the chinese spindle.

Is there something to do about this issue, can I invest in a kevlar reinforced one, go for a more narrower belt, spray with some kind of lube?

Thanks

We used belts similar to this on the Cincinnati VMCs; if the belt was too tight the air being squished out of the meshed teeth made a lot of noise.
It is also hard on the Motor Bearings. I am assuming that both shafts are parallel.
GWood