The problem of axis alignments X/Y

With circular interpolations, stepper motors knock, and lose speed. Is it possible in Linux cnc to split circular interpolation into arcs or straight lines for smooth running?

What does your G-code look like?
It is possible that you have set the axis accelerations too high, if it is causing problems for the motors.

Have you read this section of the docs?

linuxcnc.org/docs/stable/html/user/user-...#_trajectory_control