Thursday, February 17, 2011

Understanding the IE9 Software Rendering Mode

I recently heard from some users who are seeing lower-than-expected scores on the Speed Reading and FishIE Tank benchmarks. I went to check these tests myself and found that my laptop’s score was low. In fact, it was much lower than I’d seen last year. What happened?

First, a bit of background: These graphically rich demos are designed to use your PC’s Graphics Processing Unit (GPU) instead of the Central Processing Unit (CPU) to do most of the heavy lifting. Generally speaking, a faster GPU will give better performance than a slower GPU. However, there are cases where the GPU is not used for rendering, and instead the CPU is used. The primary case where this occurs is when the GPU has an outdated driver version which is not supported by the browser. In those cases, the browser will use software emulation mode, forcing the CPU to do the work instead of the GPU.
You can determine whether Internet Explorer 9 is in software mode by clicking Tools > Internet Options > Advanced. The first checkbox in the list indicates whether IE9 is running in software mode.

Read more: EricLaw's IEInternals