Your team runs a model-driven telemetry pipeline where several thousand interface counters are streamed every 5 seconds from a fleet of IOS-XE routers to a centralized collector over a dial-out gRPC subscription. The collector team reports that WAN bandwidth to the telemetry collector is saturated and CPU on the collector is high while parsing incoming messages. Management asks you to reduce on-the-wire message size and parsing overhead without changing the sensor paths or cadence. Which change to the telemetry subscription encoding best meets this requirement?