Okay, when I had civ site pop can = 400 (typical is 120), it froze on world gen with large world maxed civs and sites (y187 20min wall clock).

Vanilla:
large with min civs/sites = ~10min for 500 years.
large with maxed civs/sites = ~25min for 350 years.

Decapodia with site pop cap reduced to 120:
large with min civs/sites = ~12min for 500 years.
large with maxed civs/sites = ~30min for 350 years.

I think that is close enough to parity considering that this adds a whole new civ spreading around that I'm gonna call this fixed in 0.4.0

yea this fixed it thanks

I did some more testing and it like 1 out of 4 large worlds i make with the mod take like 20 minutes to placing civs on world gen but i do make it in unlike previously and it only does it some times.
Your other race mod doesn't lag world gen any thoughts on why the crabs do?

Roclets use basically the same initial biomes as dwarves and I think since they always start in mountains and there's plenty empty ones there aren't frequent conflicts, but Decapods start in oceans, rivers, and lakes which seem to be more contentious maybe or just the game decides a lot of them aren't suitable.

Definitely if I let them spawn in all really common biomes (which I did in early testing) the civ placing part of world gen takes less time.

Personally, I think that having the crustaceans come from the sea is worth the inconsistency at the edges of what is possible to generate anyway, but you're the one actually playing it, so let me know what you think.

its fine the mods cool and it only happens on large worlds and DF world times before steam release would take me an hour or more. was just wondering why

Does this reduce the population cap of your fortress?

Nope, just sometimes world gen would just take longer, but I haven't seen this issue in a while.