I donno if i screwed up trying to make the pak playable or it was already there (it was so long ago) But i get a new industry chain or growth every month. It is way to much but what infuences this (version 11.35)
i already found:
# The following is disabled in experimental, which has a new system
# when a city reaches 2^n times of this number
# then a factory is extended, or a new factory chain is spawned
#industry_increase_every = 2000
# The preceding is disabled in experimental
beside this i found nothing to explain the rapid growth.