Optimize Data load from customized DataSource to Cube

Dear Gurus,

We have created a customized datasource to load Currency/Exchange Rates to Cube. to load the data we have created a chain for the same. flow is as below.

1. Process type delete Data target content

2. Info package for customized data source

3. delete Index process type for cube

4. DTP with full update in process PSA -> CUBE

5. create Index process type for cube

6. PSA deletion process type

Business requirement is that we load the fresh data all the time. Source Data is very flat and so the transformation. DTP take forever to load the data.

Please advise what to do inorder to optimize this... basically how can we optimize it at the DTP Level.

Hoping for an early response.

Thanks,

Dhruv