Are you sure that this is midi jitter? I did following test – Miditrack 1 holds max monosequencer which plays16th notes. Miditrack 2 set to receive midi notes from Miditrack 1. After recording midi output from max monosequencer device I can't observe any jitter in recorded Miditrack 2 – check attached screenshot of recorded 16th. If you talk about audio buffers than this jitter most likely is introduced on interpreting midi notes by audio device and probably has nothing to do with max midi processing.