Processing the Report is taking more time than usual

Hi guys we've one customized report. This report used to take 10 minutes to process usually that's it. But now its taking more than 1.5 hour and still processing. I verified if it was due to huge data. There's no much data to process, it has usual count of data only.

The report allows to enter data, check if item is available, get tracking number from posted shipment. 

Any idea what might be the issue? Is it due to table lock or any other reason?