Cost of a slow query includes frequency, CPU, reads, waits, and user time; learn to turn SQL Server measurements into a practical tuning priority.
Finding the Most Frequently Run Queries
Most frequently run queries can consume large SQL Server resources even when each call is fast; use plan cache and Query Store to find them.
Scaling Out Read Queries
Scaling out read queries uses replicas, caches, and routing with measured freshness and operating cost; learn when each path fits.