Have you turned your map on, when you have lags?
On my system (FX-8350 / GTX 960-4GB / 8 GB RAM) ECO runs properly between 35 and 95 fps. The only time i see lags is, while i moving arround having the map turned on.
With map turned on i have 25-35 fps, with map on and max. zoom in map fps break down to ~10.