Excessive service mesh configuration drives sidecar memory usage by 50-80%

Every sidecar receives configuration for every service in the mesh by default. Each service adds clusters, endpoints, routes, and listeners to proxy memory. In large meshes (hundreds or thousands of services), this is the number one cause of high sidecar memory. Can account for 50-80% of memory usage.

Count clusters, endpoints, listeners, and routes with istioctl proxy-config commands. Apply a Sidecar resource to limit egress hosts to own namespace and istio-system only. This single change can cut memory usage by 50-80% in large meshes.