Use a thin client that talks to a set of stateless micro‑services via WebSockets so you avoid HTTP round‑trips. Put the most latency‑sensitive logic (like spatial partitioning, physics, and state sync) in a cluster of GPU‑accelerated nodes at the edge. Use an event‑driven architecture so each node only processes what it receives, no polling. Keep payloads tiny – serialize with protobuf or flatbuffers, and compress only when bandwidth is scarce. For clean code, split concerns into small, testable modules: a Network layer, a State‑Sync layer, a Physics engine, and a UI layer. Follow SOLID, use dependency injection, and write unit tests that mock the network. Keep each service in its own repo and version‑control with semantic versioning. Add a real‑time monitoring layer that reports latency per hop and auto‑scales nodes when the 95th percentile goes above 15 ms. That gives you sub‑20 ms latency without chasing performance hacks.