Thank you Amlan,
I understand your point. All this sounds good.
I looked into the files that are generated, each file has record count b/w 40 to 100. Currently all 3 files are submitted in parallel using RFKKRL00 as background job. So I am totally clueless about this large processing time.
Any clues? Does this has any relation to cash management? I see there is check for parallel update to CASH Management in SPRO->FICA->Technical Settings for mass jobs