Choosing Between Symfony HttpCache and Application-Level Cache for Concurrent Request Latency

Goal: Reduce response latency that appears only under high concurrent request volumes while preventing cache stampede when cached entries expire.

Constraint: Choose between Symfony's built-in HttpCache (gateway/reverse proxy) and application-level caching via the Cache component. Uncertainty remains about which approach better balances low latency, stampede protection, and resource consumption under realistic concurrent loads.

Specific questions:

• Does HttpCache’s stale‑while‑revalidate behavior provide sufficient stampede mitigation compared to application‑level caching with explicit lock mechanisms?
• Which option yields lower average latency under thousands of concurrent requests without exhausting PHP worker processes?
• What are the operational trade‑offs in terms of deployment complexity, memory usage, and need for external infrastructure?