Delay in SRM loads from source into BI.

I am trying to load data from SRM source into BI using Datasource PSA - 0SRM_TD_IV. It took 6hr 41 minutes to load 88383 records into the PSA, do not know the reasons why?

I know that there are performance issues with SRM extractors but can anyone explain the steps on how data is being gathered in SRM for extraction ? And could there be a solution for this ? Will award points for legible anwers.

We are on SRM 5.0. and BI 7.0

Thanks.

Ramesh