In Civup v2.0.45 (G&K) I made some internal changes to reduce the "refresh rate" of city yields in an attempt to reduce lag. It now refreshes only when specific events happen like reassigning citizens, choosing production, etc. If you encountered lag problems in the past, please post if v45 affects you, or does not have a perceptible change.
If this works I will transfer the improvements over to the VEM version of Civup.