Remember folks, Bryce 6 and 7 compress files during save. Bryce 5.5 does not compress anything. Therefore, you cannot compare file sizes between them directly. It all relates to how much ram you use when the file is running, forget the file size on disc.

Bryce 5.5, i have several scenes with 400mb. But to reach 400mb in Bryce 7 with zip compression would be a massive file indeed.