hooterville
I tried the Dev Tools and I didn't see it either. It took me a while to figure out what she was looking at, but I finally found it.
After you click to go to mail and immediately stop the page from loading (clicking X on the browser's upper left controls), press F12 like she said. Then change the options along the top row of the Dev Tools to "Network", which is the part that was left out. Then do the F5 refresh and it will start going through its thing. Make sure to wait for a minute or two after the page appears to be finished loading, as it may still be loading things that you can't see (it did for me). If you keep watching the load time you'll see what I mean. I tend to also watch my modem to make sure the activity lights appear to have stopped blinking for a bit.
I didn't put the Windows side by side like she had them, but you can still see the load time at the bottom right of the Dev Tools window.
Edit: Please disregard what's been struck through. It appears that the Dev Tools will continue to run some kind of test, using bandwidth and data on a never-ending cycle. So again, please disregard that and just note the page load time, or even take a snapshot of it, after the page has finished loading in the normal fashion. Sorry for any confusion.
