Excellent article around troubleshooting slow query performance.
This query also allows you to see historical queries executed.
SELECT TOP 100
max(last_execution_time) LastExecutionTime,
SUM(total_logical_reads) AS total_logical_reads ,
COUNT(*) AS num_queries , --number of individual queries in batch
--not all usages need be equivalent, in the case of looping
--or branching code
MAX(execution_count) AS execution_count ,
MAX(execText.text) AS queryText
FROM sys.dm_exec_query_stats deqs
CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS execText
GROUP BY deqs.sql_handle
ORDER BY 1 DESC
