The trigger speed of Touch Bar button presses is pretty sluggish. The threshold for acceptable UI latency is usually estimated at < 200ms. One thing that would help is to add an option to trigger on key down instead of key up, which has a noticeable delay.
Is this possible or is there an OS limitation here?
It should trigger pretty much instantly after releasing the touch ( <20ms), are you seeing a delay? Is it maybe the assigned action and not the triggering itself that's slow?
Triggering on touch causes even more accidental touches while typing.
In my experience any touchbar button presses happen instantly with no delay, certainly nothing like 200ms