Load testing - Too Many Requests

Hi,

we've started load testing.  

When we send 10 requests per second, EpiServer Find returns with the error: The remote server returned an error: (429) Too Many Requests.

Our production index should be able to handle up to 75 queries per second (and the developer indexes are 25 queries per second).

Is this because we are hitting the index from the same IP address or could it be a configuration issue on our side? 

Thanks