I'm not sure how you'd coordinate between multiple electron windows, but I can say that how responsive things are putting data through the datascript/posh depends greatly on how much data you have. For relatively small data, you can have a relatively rapid set of transactions flow through the system and have things update fairly responsively. I did this on an a little demo app where you can create points on an svg, and drag them around, and it was surprisingly responsible: https://github.com/metasoarous/odum