What is a key consideration when testing cross-subnet messaging performance?

• A. Cross-subnet messaging should be tested only for functionality.
• B. Performance testing should include end-to-end messaging and finality timings across subnets.
• C. Only the sender subnet matters for performance.
• D. Messaging performance is the same across all networks.

Answer: (B)

End-to-end behavior is what matters. In cross-subnet messaging, performance isn’t just about sending a message; it’s about how quickly the entire path completes—from the moment the message is emitted on one subnet, through inter-subnet relays and validator processing, to its receipt and finalization on the destination subnet. Measuring end-to-end latency, throughput, and the time to finality across subnets captures the real user-facing performance and how reliably cross-subnet coordination works under load. That’s why including end-to-end messaging and finality timings across subnets is the best approach. Testing only functionality misses timing, focusing only on the sender subnet ignores the cross-subnet path, and assuming identical performance across networks isn’t accurate.