ok, I mistitled my url on purpose.. But I thought either way it's clever that based on my browser, they knew to toss up an alert tailored to me and my preferred web browser suggesting tips on how to speed up my gmail session. See screenshot:

Upon closer inspection, they actually sniffed out my use of Firebug plugin always running.  They recommend disabling Firebug for gmail. I suppose it would be a good practice, in general, to just enable firebug for specific sites I'm working with-- what a novel idea..