Server CPU stays on 100% when e-commerce site runs

I have developed an e-commerce website on .NET umbraco. After deploying it i have made a load test with 100 users (loadimapct).When ever more than 30 users tried to access the site,it freezes and CPU usage stays at 100% till the test is over. The site is accessing an indexing engine (Fact-Finder) internally which is deployed on a Tomcat Server.
Here is a snap shot of the condition.

Snapshot

I have checked the site with profilers but there is no heavy process running that i can see.

I have made a check with DebugDiag tool (Troubleshooting High CPU in an IIS 7.x Application Pool).It indicates high CPU usage but I can't understand which page or resource from my website makes this,So i have attached a copy of report.
Detail Report Link

can any one Help on this ?