How to improve insert speed with index on text column

Hi all,

I am using Postgresql database for our project and doing some
performance testing. We need to insert millions of record with indexed
columns. We have 5 columns in table. I created index on integer only
then performance is good but when I created index on text column as
well then the performance reduced to 1/8th times. My question is how I
can improve performance when inserting data using index on text
column?

Thanks,
Saurabh