Please share demo server current configuration .

Our hosting servers are described on the site : https://www.projeqtor.org/en/product-en/technical-en/64-setup-en/412-product-prerequisites-en

Please also share the database used for demo application.

MySql

Please suggest performance parameters for postgres.

This is out of scope of the forum cometency
We are not postgreSql experts

Please also brief parameters used in demo config file.

Standard.
Just applied advised setup (put sensible files out of web reach)

So far we have no issue with overall performance with Postgressql 13 database which is optimized from our side by various parameters.
The issue is specific for New ticket creation/updation which takes long time and user are complaining only for this issue.