Marlin stuttering when exceeding the calculated/theoretical velocity maximum for the 40 kHz stepper interrupt

Marlin stuttering when exceeding the calculated/theoretical velocity maximum for the 40 kHz stepper interrupt frequency.
DRV8825 with 1/32 microstepping and 20-tooth pulley (160steps/mm), bumping up against the 250mm/s limit for single axis moves.
Limiting vmax a bit fixes the issue.

Smoothie does 100khz, if you really need it.

This bug has now been fixed in Marlin (dev).
https://github.com/MarlinFirmware/MarlinDev/issues/35
https://github.com/MarlinFirmware/MarlinDev/pull/138