VSTS is sometimes like the Franklin Institute in Philadelphia was for me as a New Jersey school kid - despite your best efforts to prove the chaperones wrong, you really can't cram it all into your 8 year old head on one field trip.  Anyway, drumroll please, something I just discovered today.  There is a funky slider at the bottom of the load test results window.  It is not standard UI component so I didn't recognize it as anything fancy at first.  Basically the line chart view above the slider demonstrates the entire history of the load test run by default.  However, the slider at the bottom represents a timeline of the entire run.  It can be adjusted from the left and from the right.  So you can select the portion of the timeline for the load test results you want to view by "cropping" the time in a way, and then it resizes the upper visible portion of the results chart to fit the selected section of the timeline.