Okay, here's how we can test it. Presumably, you've already got pipelining enabled, so grab your stopwatch and get ready. The page I used is Google's translation page - it's nice, because it's got lots of little flag gifs, and even on a fast connection it'll take a bit to load, plus it's not some totally obscure page that nobody ever sees. First, let's clear your browser cache by going to "Tools" -> "Options" -> "Privacy" and hitting "Clear" next to "Cache". Once you've done that, start timing with your watch as soon as you click on the link, and as soon as the status bar at the bottom of the browser says "Done", stop the watch.
http://www.google.com/language_tools?hl=en
Got it? Now, disable http pipelining and http proxy pipelining in about:config - return to the default settings, basically. Clear your cache again and close and restart your browser. Come back to this page here on FR, grab your stopwatch, and time the page load again. You should notice a fairly significant difference in load times, although which one is faster may surprise you ;)