Over the past six months, Grafana Mimir has undergone significant optimizations to enhance query performance and cost efficiency, particularly by reducing memory usage in the store-gateway component. This was achieved by eliminating inverted index lookups for broad matchers, which significantly reduced memory spikes that previously led to out-of-memory (OOM) errors. The optimization process involved continuous profiling and active queries tracking to identify and address memory consumption issues, notably those caused by unnecessarily loading large volumes of series IDs. By leveraging the structure of the Prometheus TSDB, Grafana Mimir was able to fetch only the necessary series and apply matchers more efficiently, resulting in a reduction of store-gateway memory utilization by up to 64% in some clusters, and a 30% reduction in memory requests across all Mimir clusters. The improvements not only stabilized query performance but also contributed to lowering the total cost of ownership (TCO) for Mimir. Future enhancements are anticipated to further refine the querying experience by adopting streaming techniques in the PromQL evaluation.