400 mS is way too much. Something is out of whack here. As Joe implied, do you have a lot of devices daisy-chained in front of the H90? Multiple MIDI Channels or Omni, a number of PCs transmitting? Trying to diagnose … I’ve had to delay MIDI for several legacy devices, but never as long as that.
For comparison, I regularly pound the H90 with CC LFOs, envelopes, sequencers, etc. from a Reflex, Beebo, MPX, 8 Step Program … Often modulating the modulation on its way in, and I’m not getting any hiccups. That same scenario to an H9 or ‘Factor pedal would freak out the display – at a minimum – or melt it down completely.