Design an application performance monitoring system.

Optimizing data transmission in APM systems involves several strategies:

1. Sampling: Instead of sending every single data point, collect a representative subset. This is particularly effective for high-volume, low-impact metrics.
2. Aggregation: Group similar data points together before sending. For instance, aggregate error counts or request durations over short time intervals.
3. Compression: Employ efficient compression algorithms (like Gzip or Brotli) to reduce the size of data payloads.
4. Batching: Send data in batches rather than individual records. This reduces network overhead and can be combined with asynchronous sending.
5. Intelligent Filtering: Configure agents to only send data that meets certain criteria (e.g., only send slow requests, or only send requests with errors).
6. Efficient Data Formats: Use compact serialization formats like Protocol Buffers or MessagePack instead of verbose formats like JSON where appropriate.
7. Edge Processing: Perform some level of data processing or filtering directly on the agent or at a local gateway before sending to the central collector.
8. Protocol Optimization: Utilize efficient network protocols and consider protocols designed for telemetry data, like OpenTelemetry's OTLP.

The choice of strategy depends on the specific type of data, the volume, and the acceptable latency for insights.