Strange Lag in one map, but not Other?

[JohnL]

I have two maps I am working on. One map lags off and on every few seconds and the other plays smoothly no issues! I have a good newer PC w/24 GB RAM, so it's not that.

What is perplexing me is that the game that lags is a much a smaller city with fewer assets. I cannot figure out what could be causing the lesser map to lag so badly? The Lagging one is 35K people and the NO-LAG map is a city of 100k with tons more assets! ??

Anyone have ideas? Also, In the no-lag map I've already used every asset I used in the map that lags, so could the map have an issue separately? Seems odd that it would.