I've been trying to find a right balance between nations loaded and no crash dumps/fastish gameplay.
I've got a few custom DB's loaded, right now I'm trying (from off the top of my head)....
chile, colombia, paraguay, peru, uruguay, argentina, brazil, USA, Mexico, ivory coast, cameroon, egypt, ghana, nigeria, algeria, tunisia, south africa, norway, slovakia, slovenia, england, france, spain, italy, germany, portugal, holland, belgium, scotland, denmark, sweden, greece, turkey, bulgaria, romania, croatia, serbia, russia, ukraine, hungary, austria, czech republic, and Saudi Arabia.
132,000 players loaded, last try, I get through a year, somewhat slowly with 146,000 and a few more leagues, but after a year I started getting a bunch of crash dumps.
I'm afraid 132k won't work, and I'll have to start cutting more nations. My aim is to improve foreign regen quality, and quality of foreign international competition (especially Africa).