The use of isolation levels in databases can significantly impact performance, and choosing the right level is crucial for achieving optimal results. YugabyteDB's decision to default to a weaker isolation level, such as Snapshot, instead of Serializable, allows it to achieve higher performance without compromising correctness. The performance difference between Snapshot and Serializable isolation levels in YugabyteDB was found to be negligible, with both isolation levels yielding comparable throughput and latency for the workloads tested. This approach prioritizes high-performance over strict ACID guarantees, which may not be necessary for all workloads. By adopting a more flexible approach to isolation levels, database vendors can cater to a broader range of use cases while maintaining performance.