30km/h is not an uncommon speed in European urban areas. For example, in France within towns 50km/h is the default speed limit for main arteries, but it is 30km/h for areas where pedestrians are expected. Most of Paris has made the switch, so has Brussels. I would go as far as saying they are a majority of streets, while yes, roads are always faster, but that would be playing semantic games.
Majority by road count, road length, road surface area, number of trips travelled or what? The answer varies. And BTW, 30km/h isn't very low speed in a country where bicycles are common.
Good news about Milan, though. That'll be such an improvement.