All of the applications are driven by a high frequency timer callback. Most of them use canvas for rendering, but some rely on animating DOM elements, and some use a combination of the two. In most applications at least portions of the code are written in the object oriented style – either in application code or in included libraries (for example, Box2d.js). Short functions are common, as are frequent property reads and writes, and polymorphism. All of the applications perform floating point arithmetic and many allocate a fair amount of memory putting pressure on the garbage collector. These common patterns became the focus of our performance work in IE10.
Source: Internet Explorer blog | Image via Microsoft