A conference talk covering advanced patterns for building high-performance distributed systems in modern C++ using Boost.Asio and Boost.Beast. Topics include: the proactor pattern and IO context event loop, C++20 coroutines as a replacement for callback-based async code, backpressure handling with bounded queues, HTTP request pipelining for throughput gains, connection lifecycle management with heartbeats, retry strategies with exponential backoff and jitter, circuit breaker pattern for graceful degradation, and common pitfalls such as accidental blocking, hidden thread contention (false sharing, global mutexes), and memory lifetime bugs. Production benchmarks cited include 5M+ events/second, sub-500µs latency, and 50K+ concurrent connections.