We have a saas system, architecture as K8s cluster (5 worker nodes), 1 cluster database postgres (3 nodes: 1 leader, 2 nodes), When the number of databases is large ( > 3000 databases), then database postgresql cluster crashes constantly. We guess because the number of transactions increased, I need to support or related link to give me any ideas.

How to design architecture for large system as saas?

Thank you very much in advance,

Regards