A website's loading time is determined by all of these factors. If one or several links in the chain fail to deliver in time, there's no way to determine the speed of a browser. Therefore, judging a browser by its scripting performance or overall website display speed is -- in my opinion -- an extremely theoretical undertaking with little to no effect on any real-world scenario. And even if browser speed made a visible difference, you'd have to set up a local web server on your own PC and measure browsing speeds for local websites in order to avoid most (not all!) of the factors described above.

Then there's the factor of browser behavior: how do power users actually use a browser? Well, maybe we browse to a website and use a middle- or Ctrl-click to open one or many links in new tabs while we keep reading the current website. In the background, another website is loading, and will likely be ready and waiting for us once we're done reading the active page. That's just one of many different user routines. We're not all robots who type in the URL of a website and wait for it to fully load until we're able to read it. Of course, I don't want to make superficial statements about everyone's browsing habits, but you need to take a good look on how you actually surf the web before choosing your browser based on precise speeds.

Let's put the issue of classic speed tests aside. What (most) of the popular web browser comparisons neglect is that today's browser generation has become more resource intensive than ever. Operating systems like Windows 8 have become increasingly "slimmer" in order to fit on lower end or low-powered mobile devices (tablets, first-generation ultrabooks) or thin clients. One the other side, the browser, which is arguably the most important application on any PC, has become more bloated. And while a big memory footprint on high-end systems may only result in some annoying lag or crashes, it affects the performance of the aforementioned devices, including battery life and overall responsiveness, drastically. And that has a visible effect on your web browsing experience.

Running 15 tabs in your browser isn't an uncommon scenario, right? Have you ever taken a good look at your Task Manager while doing so? On one of my test beds (a 3 GHz Core 2 Duo machine with 4 GB of memory running Windows 7 SP1), Internet Explorer 9 with 15 tabs open takes up a whopping 1,056 MB of RAM. That's a gig of RAM that's being taken up just by a seemingly small application. Plus, these 15 tabs caused IE9 to create nine iexplore.exe processes, each taking up more (basic process units to which the OS allocates processor time) and (the amount of OS resources being accessed) than any other application or service that's running on most systems. Again, on faster machines with tons of memory, this resource hogging will manifest as reliability issues -- some lags and crashes. On netbooks, laptops, older desktops, first-generation ultrabooks, and tablets, it will cause noticeable performance problems.