I think there was a hard limit of the number of posts on the last version of the forum software for one thread wasn’t there ? Same case with this new version? @Roger
Not so much a hard limit, but the database structure was poor with vBulletin and performance went down exponentially as the number of posts on a thread increased so we limited it to around 1000 or so. That isn't a problem on Xenforo software which we have been running for about 8 years now.