without -O3 and the armv7e optimizations ( std. Makefile in github repo ):
1 stepper:
lowest ticks: 44
3 stepper:
lowest ticks: 198
with -O3 and the armv7e optimizations ( -mtune=cortex-m7 -march=armv7e-m+fp.dp -mcpu=cortex-m7 ):
1 stepper:
lowest ticks: 42
3 stepper:
lowest ticks: 192