MIDI input / LED strip display timing issue

Other Hardware LEDs and Multiplexing
9

I have:

if (MIDI.read()) {
    MIDIread = MIDI.read();
    shown = false;
    location_byte = MIDI.getType();
    channel = MIDI.getChannel();
    note = MIDI.getData1();
    if (location_byte == midi_on || location_byte == midi_off) newNote = true;
  
    if (newNote) {
      if (location_byte == midi_on) {
        midiNote[channel][note] = 1;
      }
      if (location_byte == midi_off) {
        midiNote[channel][note] = 0;
      }
      newNote = false;
    }
  }

...and then at the end:

if (!MIDIread && !shown) {
  FastLED.show();
  shown = true;
  MIDIread = false;
}