get the top-10 queries that are taking the most CPU per execution

SELECT TOP 10
total_worker_time/execution_count AS avg_cpu_cost, plan_handle,
execution_count,
(SELECT SUBSTRING(text, statement_start_offset/2 + 1,
(CASE WHEN statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max), text)) * 2
ELSE statement_end_offset
END - statement_start_offset)/2)
FROM sys.dm_exec_sql_text(sql_handle)) AS query_text
FROM sys.dm_exec_query_stats
ORDER BY [avg_cpu_cost] DESC

If you use the above DMV, you may miss finding the most frequently executed queries in your workload if the CPU cost of those queries is much less than say top-10 queries. To find the most frequently executed queries in your workload, you can execute the following DMV query, a slight variant of the previous DMV query:

2.

 SELECT TOP 10 total_worker_time, plan_handle,execution_count,
(SELECT SUBSTRING(text, statement_start_offset/2 + 1,
(CASE WHEN statement_end_offset = -1
THEN LEN(CONVERT(nvarchar(max),text)) * 2
ELSE statement_end_offset
END - statement_start_offset)/2)
FROM sys.dm_exec_sql_text(sql_handle)) AS query_text
FROM sys.dm_exec_query_stats
ORDER BY execution_count DESC