I was speaking to Brian Barker about this at the UK Model Exhibition. I understand that the disproportionate delay on M3 has been fixed.
If you are wanting a faster response that the activate/deactivate, then are the step and dir controls any faster - and use the A axis as a driver for the laser - using a G0 command. The difficulty would be in the time "on" since this would have to be equated to the distance the A axis supposedly moved - but it seems this could be relatively easily calculated. If the "step" pin was used (to fire a retriggerable monostable) the "distance" travelled could be gradually reduced to give the minimum "fire" time - or indeed the monostable could be hardwired to give the time directly.