This metric calculates the total number of transactions per second across all databases on the monitored instance.
This metric uses the counter Transactions/sec from the SQL Server Databases counter object and _Total instance. On SQL Server 2000 instances, this counter is available through sysperfinfo. On SQL Server 2005 or later instances, this counter is available through sys.dm_os_performance_counters.
This rate is a measurement of throughput on the processor, as determined by the SQL Server workload. Although this rate measures activity within a transaction, and a higher transaction rate indicates a higher risk of resource issues, it does not account for all activity on the SQL Server computer.