Latency Critical Systems

Use this skill when the user cares about realtime behavior, hot paths, streaming freshness, or execution speed. This includes HFT-like infrastructure, but the skill is engineering-focused. It does not authorize live trading or financial advice.

Split The Metrics

Do not collapse everything into "fast." Track:

• p50, p95, and p99 latency;
• throughput;
• freshness age;
• queue depth;
• cache hit rate;
• provider/API response time;
• browser render time;
• correctness under load;
• failure and retry behavior.

Map The Hot Path

Write the path from user/event to final visible state:

source event -> provider API -> ingest worker -> queue -> cache -> edge route
-> client stream -> browser render -> user-visible state

Then measure each segment separately.

Optimization Order

1. Remove unnecessary round trips.
2. Cache stable reads with freshness metadata.
3. Batch small calls and writes.
4. Move compute closer to the data or the user.
5. Split hot and cold paths.
6. Apply backpressure before queues grow unbounded.