Disk I/O is most of the time the bottleneck of your SQL database, even when using SSD. The SQL statement below will show you the most heavy disk I/O statements, which you should improve.
SELECT TOP 20 (total_logical_reads + total_logical_writes) / qs.execution_count AS average_IO, (total_logical_reads + total_logical_writes) AS total_IO, qs.execution_count AS execution_count, SUBSTRING (qt.text,qs.statement_start_offset/2, (CASE WHEN qs.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2 ELSE qs.statement_end_offset END - qs.statement_start_offset)/2) AS indivudual_query, o.name AS object_name, DB_NAME(qt.dbid) AS database_name FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as qt LEFT OUTER JOIN sys.objects o ON qt.objectid = o.object_id where qt.dbid = DB_ID() ORDER BY average_IO DESC;