Here’s a possible bug I’ve observed:
When performing tests of my site, I’ve observed that my Start Render improves dramatically when I select the Video > Capture Video feature.
This is an unexpected result. I would expect the test results to be unaffected by this test feature.
Here are couple of examples. The first is a test from Los Angeles. First with, and then without, the video selected. And the test after that one compares the same from New Zealand.
Please observe how the selection of the video improves Start Render. It completely changes the relationship between the vertical Green line (Start Render) and the vertical Blue line (Load Time) on the following screenshots.
[color=#0000CD]Los Angeles, no video[/color] http://www.webpagetest.org/result/110331_9B_9PZV/
[color=#0000CD]Los Angeles, Capture Video is selected[/color] http://www.webpagetest.org/result/110331_2T_9PYS/
[color=#0000CD]New Zealand, no video[/color] http://www.webpagetest.org/result/110331_BY_9PZJ/
[color=#0000CD]New Zealand, Capture Video is selected[/color] http://www.webpagetest.org/result/110331_PB_9Q2X/