Hi all i have noticed for awhile. That when you get that sound as a road or building is complete mainly roads then the graphic of the dust it continually freezes the game some time foe up to 6-8 secounds then otheres as you are scroling freezes the scrolling for a bit. Anyone else having this issue 400 plus pop at the moment.
When a new road becomes available, routing options need to update: can villagers take a more efficient route to where they are going? What is the quickest route to the nearest storage for whatever your villager is doing?
As your number of villagers increases, this calculation becomes heavier and heavier as it is calculated for all travellers (villagers / visiting merchants / wildlife)
If this causes noticeable lag depends on your computer’s calculating power (and available memory).
I found it useful to switch off other applications that are running in the background.