Simultaneous movement in several axes

Hi all! I'm building a 3D printer where the A-axis drives the extruder. I encountered such a problem, if the movement is without the A axis, then the program is executed correctly, but if the A axis is used during the movement, then the speed graph changes shape and the movement becomes small jerks. Equipment used: X86 PC, MECA 7I92, stepper drivers and stepper motors. What I tried to change: computer, set high speed/acceleration of the A axis, type of the A axis linear/rotary, change the A axis to the U axis, set a very small step scale. But I didn't succeed.I took X-axis motion waveforms with and without an extruder and I don't understand why they are different?In this case, the use / non-use of the Y and Z axes does not affect the speed / acceleration of movement.

For 3d printing try to use the Z axis word for the extruder and the A axis word for the hight.
The reason is that for any coordinated move involving more than XYZ the trajectory planner falls back to single line look ahead, which can lead to jerky movement. Using the A axis for the hight is much less prone to cause issues since it is only used to move from one layer to the next.

[edit]
see discussion here:
forum.linuxcnc.org/38-general-linuxcnc-q...ding-issues?start=20

Thanks for the link Aciera. It's a pity that the motion planner is designed this way, as linuxcnc is otherwise very interesting software. Replacing the extruder axis with the Z axis will not work in my case, because my printer works on non-linear surfaces. I hope this bug will be fixed in the future. Are there any other CNC systems that work with MESA 7I92 cards?