try using Ableton live (or free daw software) to mix multiple midi inputs, map each one to a different channel, then send midi out to Resolume. will not take up ressourses if no audio files in daw (digital audio workstation). i'm able to send midi from lauchpad and novation nocturn at the same time....
it's a ableton problem, i've had it too. It has something to do with midi info coming into ableton then "re-directed" to midi output. I remember solving this buy making the midi input attache to a ableton function, then get the midi out to resolume. I'll get back to u on this if not solved...
huum, i would say that a top of the line mac with a fast ssd would get the job done better with syphon , and thats why i raise the question : Mac OS is moving audio and midi and video between applications without allmost any hit on cpu or gpu , and this is getting annoying to the other community :) ...