Explore a 20-minute conference talk from USENIX OSDI '20 that delves into performance-optimal read-only transactions in distributed storage systems. Learn about the three properties of simple reads necessary for optimal performance and discover the fundamental tradeoff between performance optimality and strict serializability. Examine PORT, a novel design offering the strongest consistency to date, and its key component, version clocks. Gain insights into two practical applications: Scylla-PORT and Eiger-PORT, demonstrating improved performance in process-ordered serializability and causal consistency scenarios. Understand the challenges and solutions in achieving efficient read-only transactions across distributed systems.