In case this is of interest I have been experimenting - so - Mr Bond - I can tell you this:-
In the VB challenge - free sailing mode runs fluidly with the other 2 vessels but the barge slows it very muchly.
I have 'stolen' the barge and grafted it onto SS08 (which of course it was never meant to be compatible with). It runs at good framerates here, all bridge screens and controls work OK but it displays at much reduced draught and tries to sail in circles. Point is it displays OK and tries to obey all commands. One big difference though, it has an 'invisible' bridge structure - that is the controls and consoles can be seen from inside and outside views but the bridge superstructure can't (so SS08 doesn't read the extra 'gene' that displays this). That is the big difference between this and other ships so maybe it is what causes all the display problems some of us have.