Hi Jhansi,
Please compare the present job details with old job which is older than 3months.
Is any changes happens on master data load schedule times? Actually from this table RSSTATMANREQMAP, dtp may reads sid and source req info. if you not loaded master data before the transaction loads, there might be cause.
Please check dimension table sizes for respective cube thru SE38 - SAP_INFOCUBE_DESIGNS.
As my guess if any dim table exceeding 20% of the fact table then this may leads slow performance here. in that situation we need consider Line Item Dimension concept.
Thanks