ardour4 vs midi control surfaces (slew rate limiting?)

Hi,

I've seen this behavior before in Ardour3 but it still happens in 4.

Let's say I enable generic MIDI control, hook up a BCF2000 through the 
a2jmidid -e command and bind a fader to the master fader of a session.

If I move the physical fader in the BCF2000 slowly all is good. If it 
goes beyond a certain "slew rate" the fader in Ardour gets stuck and 
stops reacting to (fast) movements of the physical fader. It only starts 
moving again if I slow down my movements and cross the last value stored 
by Ardour. It then follows the physical fader again until I move it too 
fast and it gets stuck again.

Is there a midi command rate limit somewhere in the code? A preference I 
might use to turn off this behavior? Maybe a "feature" of a2jmidid?

This makes it unusable for a "live" mixer situation (and I have to 
revert to Ardour2 which does not have this problem).

Weird...
-- Fernando