Modern enterprise applications increasingly rely on distributed architectures to support scalability, availability, and continuous service delivery. While distributing services across multiple nodes improves flexibility and throughput, it also introduces complex challenges in performance optimization and system reliability. Network latency, partial failures, service dependencies, and inconsistent data states become common operational concerns. This review examines the core performance and reliability factors affecting distributed enterprise systems, including communication overhead, consistency models, fault tolerance mechanisms, observability, and resilience patterns. The article further discusses architectural strategies such as microservices, event-driven design, caching, load balancing, circuit breaking, and graceful degradation. Finally, best-practice recommendations are provided to help engineers design systems that maintain high throughput while remaining fault-tolerant under real-world production conditions.