Thanks for your replies.

Yes I am using the parallel port of a Sony Vaio Pentium 4 laptop. One thing I notice is that I get an occasional delay when jogging if the wi-fi is active. So I disable it when running.

Motors are 4nm nema 24. One pair for the main gantry (y axis) is driven from 80V and the x axis and z axis are driven from 50V. I thought the lighter weight would need less voltage but I think I probably made a mistake there as I suspect voltage directly affects motor top speed, while current affects torque? In which case my x axis will not be able to reach such a high RPM as the Y axis even though it has less weight to move.

I made a video just now. I must admit there are no problems with it in this case, lol! But I think it shows my point that the direction changes are fast at the center of the circle. This was at 2000mm/min. Circles do seem less round at higher speed and more round at lower speed. In this project I need to cut some 6mm holes and use a 3mm cutter, so the gantry will need to make very small adjustments and fast if the feedrate is high.

Anyway here it is, be gentle!

https://youtu.be/3mmX7BZWEjQ