Vladimir, one of the coders working on Firefox 3, was having some trouble overcoming a few performance issues in the builds. He did a little investigation, resulting in the chart above and others, and found that Firefox’s display rate appeared to be being throttled by the OS for no particular reason. The problem didn’t affect Safari, and it wasn’t until he dug deep into Webkit’s coding crevasses that he found the solution: a set of special instructions and shortcuts so poorly documented that they may as well be secret. He worked some in (just a few lines) and Firefox exploded out of the gate.
Vlad doesn’t think this code was hidden maliciously, but it seems at least to be a little negligent on Apple’s part to bury these so deep. Of course, I’m not a coder and I don’t know what I’m talking about.