Articulation names <5 letters slow switching PrCh

OSX 10.10.5, C9.5.1 (but same bug was on C8.5 in 2015), track’s output connected to the Plogue Bidule patch, in which PrCh messages switches out to different instruments.
A different same patch, made on C++ works good with any number of letters in Expression maps, but it seems, that this patch is critical sensitive to switching speed - so, it’s strange, why speed depends on the articulation name?