Using this query you can easy to track that, Which running SQL Query is taking extra time or load, check reads and writes.
Output will be.
Query
SELECT es.session_id
,es.program_name
,es.login_name
,es.nt_user_name
,es.login_time
,es.host_name
,es.cpu_time
,es.total_scheduled_time
,es.total_elapsed_time
,es.memory_usage
,es.logical_reads
,es.reads
,es.writes
,st.text
FROM sys.dm_exec_sessions es
LEFT JOIN sys.dm_exec_connections ec
ON es.session_id = ec.session_id
LEFT JOIN sys.dm_exec_requests er
ON es.session_id = er.session_id
OUTER APPLY sys.dm_exec_sql_text (er.sql_handle) st
WHERE es.session_id > 50 -- < 50 system sessions
ORDER BY es.cpu_time DESC