Finally, I have found that where API is getting slow,
Please follow the steps to reproduce the issue
1 – Configure Jmeter with login API ( 50 requests/ per second)
2 – Start Jmeter
3 – call login API from any other rest client (Ex: postman), You will get the new token (Jmeter should be run when generating this token)
4 – call any other API with the newly generated token (API will take more time to response)
If you try with step 4 with any old token, there is no performance issue.