Grafana Labs has transitioned from contributing to Cortex, a scalable storage solution for Prometheus, to launching Grafana Mimir, which allows for greater scalability. At KubeCon + CloudNativeCon in Barcelona, a session by Grafana Labs' Tom Wilkie and Weaveworks' Bryan Boreham showcased optimizations to Cortex's query performance, highlighting how the integration of the Prometheus PromQL engine with a scale-out storage engine ensures feature compatibility with Prometheus queries. The optimizations include batch iterators for merging results, extensive caching to reduce query latency, query parallelization, and the introduction of a query frontend that aligns, splits, caches, and queues queries. These enhancements have led to significant improvements, with Cortex achieving average response times of less than 50 milliseconds in Grafana Cloud. Despite the progress, further collaborations, particularly with the Thanos team, are planned to enhance performance for high-cardinality workloads, reflecting the project's evolution from focusing on ingestion challenges to prioritizing query performance.