jStepper VS Teacup_Firmware

Then I found the jStepper library which uses hardware-timers and interrupts to achieve high stepping rates. It uses direct port manipulation which is 30-50 faster as the digitalWrite() function what I have read.

There are several stepper libraries availiable, if you don't need a high speed then is the AccelStepper library probably what you want. If high speed is required, then I would look at the jStepper library.

Ooh another fun one you may be interested in is how I wrote Teacup's config handling - the user has to provide a config.h with various macros defining their machine setup, and then multiple separate parts of the codebase redefine those macros and re-include the file to build various structures and constants at compile-time

Since then I've made lots of things like audio amplifiers and effects, motor controllers, 3d printer controllers and firmware (and subsequently smoothieboard), muscle stimulators, bluetooth LED strip controllers, etc

Teacup can go pretty fast too, I think I've seen it clocked at 48k @ 20MHz although that may have been across 4 motors at once.

See here and here for an example from my ESC project, or this example from Teacup

https://www.airspayce.com/mikem/arduino/AccelStepper/classAccelStepper.html says "The fastest motor speed that can be reliably supported is about 4000 steps per second at a clock frequency of 16 MHz on Arduino" which is pretty poor - teacup can hit something like 10× that when controlling 4 steppers, and also comes with a non-blocking state machine based gcode parser ;)

Teacup had decent performance last time I checked, but it's more a complete firmware project rather than a library.

That's hard enough just with linear acceleration let alone complex functions - might be worth converting it to line segments host-side and just streaming basic gcode to a 3D printer firmware over the serial port.

Last time I checked, Teacup can do something like 40kHz on an atmega - might be worth having a play with that?

AccelStepper may interest you, and I think Teacup can go even faster.

The latest what? Teacup? Marlin? Aprinter? Repetier? GRBL? Something else?