Yes, if you don't find any issue with the resource utilization & the disks or the HW, then the issue could be contention at database side, the application code &...

Index rebuild is good if the index fragmentation is high, Index reorganize is suitable if the index fragmentation is very low between 5% and 30%. Please, check the index fragmentation...

Review the execution plan of that SP and the access mode of that particular table. Could be a table level lock due to full-table scan. Add appropriate index to...