I'm attempting to use ESS for realtime synthesis of notes at particular frequencies (in Hz). There are various microtonal tuning systems that I would like to implement interactively, but ESS seems to choke on the synthesis, which results in both the sound and the graphics I am displaying being grossly delayed.

To keep the processor load down, I'd like to instead send MIDI outputs to a Waldorf Pulse synthesizer (or any hardware synthesizer, for that matter). I know how to use proMIDI, but not how to define specific frequencies with it. MIDI seems to work with specific notes, and detuning amounts, but not by using just intonation to speak to a synth in Hz values. Has anybody done anything like this that could offer me some advice on either the ESS problems or the microtonal MIDI implementation?

Thanks,
Noah

If you still want to use the midi + hardware setup, you will have to use a synth that allows microtuning.  As you noted, MIDI notes don't change.  But the sound they trigger CAN change, depending on the micro tuning abilities of the synth.

I'm not sure if your Pulse allows microtuning (I tend to think not) but there are lots of synths that do.  Two that do are the Kurzweil K2000 and the Korg Triton.

Similarly, to generate the sound you could use a softsynth, possibly a free one.  Or use maxMsp/Pure Data.  (Thats what I would do.. for TOTAL CONTROL ;]  )