I'm not sure if you're already doing this, or if it's relevant to you, but a possible way to improve performance is to allow a "window" of commands that you hav

I'm not sure if you're already doing this, or if it's relevant to you, but a possible way to improve performance is to allow a "window" of commands that you haven't received an "ok" for. I believe common host software for RepRaps just allows one command at a time. How to define the window correctly depends on how the firmware does the buffering (in terms of bytes, or complete commands, or both).