I am getting error as - There are too many active security negotiations or secure conversations at the service

I have deployed CRM in cluster environment along with multiple WCF service hosted on other website.

I am performing a load test on my WCF service which are internally referring CRM Sdk and making a call to MS CRM.

The scenario for a load test

Create Account with 100 user load

Create Cases with 100 user load

Create Quotes with 100 user load

Now when I am introducing another load test as

Search Account with 100 user load

I am getting <b> active security negotiations exception</b> from organization.svc of MS CRM as a fault with server too busy.