How do you turn off expansions?

Windows Version Number: 11 pro 25h2
App Version: civ 4.1

I would like to turn off expansions, in particular the Federation & Empire Expansion. My game crawls now at AI turns, can take upwards to 5 minutes from the end of my turn to the start of the next. I typically play huge maps with 8 opponents, have 32 gig of memory and a decent but older computer now (AMD Ryzen 9 & 4080rx) and until this latest expansion had not had any issues.