in 10.11 and a beta of 10.11.1, I get a 100% cpu usage (of a total 800% with my machine) in the midiserver process with the HDSPe FX MIDI.plugin installed.  Removing it from the plugin folder drops the usage back to it's normal sub 1%.  This was not the normal behavior in 10.10.  Mac Pro 2008 8 core 2.8ghz, 3,1 machine.  I don't use MIDI with my MADI FX (I don't have the daughter card installed) so it's not a problem for me, just passing on the news..  all other MADI FX software seems great, and 10.11 really is faster for me on this old machine..