Probably hardware acceleration

http://blogs.msdn.com/b/ie/archive/2010/04/07/a-closer-look-...

Every browser vendor has their own benchmarks (Google has Octane, Mozilla has Kraken, MS has plenty of smaller ones on their IE test drive site). Apparently those are the things each vendor optimises for which shows in the results (Chrome is fastest in Octane, Firefox is fastest in Kraken, etc.). It's not so much that Chrome is slow at graphics or IE is slow doing computational stuff, it's more that each test's performance depends a little on the intricacies and internal workings of the browser it was written for (and runs best). Or maybe vice-cersa, i.e. the test was written and the browser adapted to run it fast.

For the penguins I noticed a few graphics glitches on IE 10, though, namely that penguins sliding in from the bottom or right are not rendered completely immediately, so you get only half a penguin until it redraws completely. In other sites IE tends to skip frames to keep up with rendering sometimes (although that was on an old Intel graphics chip, so might not have been that comparable).