I admit I didn't read through all 15 pages of comments before posting this, but after reading 4 of them I decided that there is probably little risk of me being entirely redundant.
I would love to see a cross OS test for the browsers that support it. I use both a Mac and PC everyday, and have used all of the browsers on both, but I admit that my software know-how is a little lacking compared to my hardware skills, so I have never run a full gamut of tests. Besides, if you did the test more people would benefit then me. Anyway, I would like to see official results because I have noticed a few things that I would like to be able to quantify, and have a solid source to point to. First off, I know for a fact these results would be extremely different on a Mac. I first started using Safari on my PC because of how blistering fast it is on my admittedly outdated Dual 1GHz G4 tower, and even on my 'obsolete' 400 MHz G3 Powerbook, but on the PC it lags a bit behind (especially on Facebook, and speed isn't the only issue there). This can easily be attributed to the fact that Apple makes OSX and Safari, so they will work better together, and everybody else has more experience programming for the PC due to its market share, so the opposite is true as well. What I would like to see is how each browser compares directly to its counterpart on the other system PC Opera v. Mac Opera, PC Safari v. Mac Safari, etc. Not just a, "Chrome is the fastest on the PC, but Safari is the fastest on the Mac.", but "Safari edges out Chrome on the Mac, but Chrome for the PC is still faster then Safari is on the Mac." (Of course I could make the comparisons myself by looking at the numbers, and I am perfectly willing to, but I think that there are a number of other people that would enjoy seeing those comparisons that wouldn't think to make them on their own.)
Next, it amazes me how many people get all fussy when someone else simply states that they prefer a different browser over their favorite (and this relates to the OS wars too!). Some people prefer one browser (or OS) because they feel more comfortable using it, or maybe there is one key feature they can't live without. In many cases, the wizz-bang features of one browser (or, you guessed it, OS) are more then a certain person needs, and they might be driven away by them. Especially when fanboys constantly hound them about the features the already know they don't need, or want! Which then leads to contention, and of course, flame wars. Everybody should have something to be proud of; they should have something in their life they can stand by, but a piece of software isn't that important! The computing community, especially these online forums, would be so much better if we could all learn to give up a little bit of our pride and learn to accept that each of us are different, and are free to choose whatever piece of software (or hardware, since this is Tom's Hardware, as yoy0yo pointed out) that best fits our needs. I, for example, have every last of the five browsers tested installed on my PC. I use them all (except IE, that is installed only for rare uses) for one feature or another that makes some particular task easier or more enjoyable. Each serves its purpose, each purpose is served, and none is left behind as the work is done.
Okay, I'm off my soapbox.
Thank you Adam for the excellent article, and all of the hard work keeping it up to date as all new versions of the browsers came out. Cheers!