AWS RDS Aurora latency baseline

Hello, In the documentation it says that the latency between different AZ is 1 to 2 milliseconds

https://docs.aws.amazon.com/sap/latest/general/arch-guide-architecture-guidelines-and-decisions.html (See Latency across Availability Zones)

There's a caveat. If you're only using the low-end instances like t2, you will likely have a lot of jitter and can sometimes encounter more latency.

If the instances are ENA (or SR-IOV) compatible, and using it, you'll get a big reduction in actual jitter and can realistically expect very low latency so long as you stay within the same VPC and region.

RDS specifically seems to be well optimized for networking, in the few years I've been using it (us-west-2) I've never had a single problem related to latency with the RDS instances themselves, but this is a N=1 data point.

Also, If you're using many instances connecting to one postgres server, make sure you're using pgbouncer or a similar connection pooler or you'll hit connection issues way before even a few ms of latency will cause problems.