The plugins - whether PC or Mac - are currently extremely slow to generate backing parts because - apparently in discussion with Pipeline it seems BBM4 is writing out the tracks to disk after regeneration (in order to be drag and droppable into a DAW ) - whereas the standalone version generates just into RAM which is much faster.
if the plugin was to stream audio from BBM4 directly after the BBM4 - not writing anything to disk but merely playing back audio into the DAW then things ought to be exactly the same generation time-wise as BIAB standalone.

Although it would be useful to be able to drag audio into DAW tracks in the end, during the music creation phase where many changes are being made to the BIAB song arrangement and chord progression - it is poor workflow to have to re-drag the tracks every time any change is made.

Instead an option to stream audio in multichannel mode should be added quickly - along with all generation - as an option - being done to RAM in BBM4 and skipping all the writing to disk until truly necessary.

This new plugin shouldnt be considered just a nice to have "icing on the cake" but the future of BIAB. At least to me that's the case.

Biab can generate up 7 tracks into RAM but you have 21 tracks in the Biab Plugin.
I suppose it could generate up the 7 style tracks into RAM but then if you want the extra tracks like multiriffs it would have to open another instance of BBW4/BB4 ?
As mentioned before, maybe the Biab Plugin could read the RAM that BBW4/BB4 writes directly, that way the BBW4/BB4 could be modified to write more tracks to another section of RAM using the same instance.

LOL But I think they have enough on their ToDoList at the moment to keep em going til 2030