While fetching data from one of NetSuite Dataset, each call returns only 1000 records as per NetSuite's policy and it takes around 1.45 minutes for each call. Let's assume if we want massive data arround 300K rows, in this case time will be increased to hours. Is there any possibility in NetSuite to reduce the time?

How are you making this call?

REST API Call using OAuth 1.0

What does the call look like? Could you perhaps limit the number of columns it should return?

1.45 minutes? Seems really long. Are you carrying out complex joins in the REST call? It may be wiser to retrieve each of the entities' data separately and do the joining on your destination database