I am also a comp sci prof. Rest assured, this issue has been on the Wishlist since the beginning of this user forum in the mid-90s. The registration dates you see with our names are from the revised forum software; several of us go much further back.

You can't know this yet, but PG Music has an excellent record of making user-requested changes, so we have to assume this one is just too integrated into the core of the program to fix easily. Remember that the program you see now has evolved with one or two major revisions every year since 1990. I agree with you that the measure limit for MIDI could be far larger without affecting the speed of song generation, and your guess about RealTracks generating slower is possibly correct, except that it was not related; as I mentioned, this limit has been with the program since the beginning (or at least version 3, when I first saw it).

As Noel mentioned, the included program RealBand can generate songs in a very similar way to BIAB, and does not have the 255 measure limit.

BIAB 2024 Win Audiophile. Software: Studio One 6.5 Pro, Swam horns, Acoustica-7, Notion 6; Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus Studio 192, Presonus Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors