In firmware 1.21 and earlier, the MaxReps figure in the M122 report would indicate whether you were pushing the controller too fast. MaxReps of 50 or less was good, 100 was just about OK, more than 100 means that you need to reduce speed and/or microstepping. A side effect of MaxReps getting too high was web interface disconnections, because the MCU was spending all its time generating step pulses, leaving no time to service the network interface.
In firmware 2.0 MaxReps is monitored dynamically. If it gets too high, a short pause is inserted. But it looks like I need to do some more work on this. I think I understand what is going on and I will fix it in the next RC.
