Best stress/load testing for SharePoint 2010 that's easy and free

Hi,

I've been looking at Visual Stupid Ultimate 2012 to perform load testing on our SharePoint farm but have been unsuccessful (so I thought).  I ran out-of-box test using URL recording.  The results show some information which I can't interpret.  It also shows 900 errors which are all related to socketexception error where web links cound't be connected.  I tried to access those links on the machine which has VS installed and they all worked fine.

URL is https but we have F5 doing SSL offloading.  Not sure if this would was the cause of the error.  Even though those links couldn't be reached, the test completed and we have results showing.

Can anyone suggest/help me with either using VS 2012 properly and interpreting the results or recommend something easier to use?

Many thanks.