I believe it's not mentioned anywhere by Google. May be some personal practical observation?

CodePudding user response：

As stated in the official documentation:

App Engine is regional, which means the infrastructure that runs your apps is located in a specific region, and Google manages it so that it is available redundantly across all of the zones within that region.

Meeting your latency, availability, or durability requirements are primary factors for selecting the region where your apps are run. You can generally select the region nearest to your app's users, but you should consider the locations where App Engine is available as well as the locations of the other Google Cloud products and services that your app uses. Using services across multiple locations can affect your app's latency as well as its pricing.

Additionally, actual latency observed in practice will depend on your application, where your resources are deployed and which GCP services you consume.

Tools such as Trace can help you profile your App Engine applications for latency.