OS X Mountain Lion
Our current cross-platform test system provides unusually low Web results under OS X Mountain Lion compared to other operating systems. While the OS X browser scores appear to be accurate in relation to each other, none of the OS X scores should be used to draw conclusions about OS X versus the other desktop environments in this test. Until we can pin down the culprit, please view the OS X results as if they were obtained on an entirely different test system.
With a perfectly smooth background animation, Apple Safari manages to pass Microsoft's new benchmark with flying colors on OS X. Believe it or not, minor-league browser Sleipnir also does quite well. Although not perfectly fluid like Safari or IE10, Sleipnir is a long way from the chop-fest presented by Chrome, Firefox, and Maxthon. Like its Windows counterpart, the OS X version of Opera does not display the animated background at all.
The following video contains a sample iteration of all six OS X browsers:
The original RoboHornet would not run on iOS, but Microsoft's version does. And how!
Each of these third-party iOS browsers are essentially just a new GUI and additional functionality added to Safari, so it makes perfect sense that vanilla Safari is the quickest of the bunch.
Opera Mini, and ostensibly any of the "Mini" browsers (such as Skyfire) that perform browser workloads on a remote server cannot run RoboHornet Pro, and therefore could not be included.