Ah, but their Box Model is miles faster. Common sense would tell you that knowing an element specified to have a width:100px will actually take up 100px on the

Ah, but their Box Model is miles faster. Common sense would tell you that knowing an element specified to have a width:100px will actually take up 100px on the screen will speed up rendering. Actual practice shows that it is indeed really fast. There's a reason why Twiddla is so fast on IE. It's because we intentionally leave the Doctype of the whiteboard, thus enabling IE to use its fast Quirksmode rendering engine. Testing showed that adding a Doctype didn't effect FF or Chrome performance at all, but simply slowed IE down to their level.