pen lag

I have a Cintiq pro 24, it's 3 months old, and never a problem. Ive just finished a big project, and suddenly noticed the pen is lagging just a fraction when im using the brush, it doesn't start when I make a stroke for a good second. Ive tried new driver, new nib, calibration, nothing has worked yet.

Can you help, 

my Mac is on OS Ventura 13.5.2