** Lang.ai's team successfully implemented performance monitoring for GraphQL resolvers using Sentry, a popular error monitoring tool. They created a custom Apollo plugin to instrument each resolver with a unique transaction ID and context, allowing them to monitor the performance of individual queries without adding explicit start and stop lines of code. The solution enables fine-grained information about query execution and Distributed Tracing capabilities. By leveraging Sentry's features, Lang.ai can now better debug and optimize complex GraphQL queries, ensuring improved overall system performance.