POSTGRES : Data import

DB Version : 13.x 1. Source table schema\

CREATE TABLE mig_bus_data
          mig_id  SERIAL,
          mig_data JSONB

2. Target table schema\

CREATE TABLE BUSINESS
       id   UNIQUE SERIAL,
      data1  ,
      data2  ,
      .
      .

3. All indexes on target table dropped 4. Data being imported in blocks of 100 records in parallel using\ Process 1

CURSOR 
     select mig_data from mig_bus_data LIMIT 100  OFFSET 0

Process 2

CURSOR 
     select mig_data from mig_bus_data LIMIT 100  OFFSET 100
   .
   .

Notes : 1. After dropping indexes and doing step 4, there is no significant performance gain. Any pointer to increase speed would help.