I downloaded the IE9 beta a week or so ago. Though it looked pretty good, the performance was less than stellar. When I looked at the options dialog, I saw that ‘Use software rendering instead of GPU rendering’ was checked and also disabled, which made unchecking it quite difficult. Apparently it will be disabled if Internet Explorer decides your graphics card isn’t good enough. I’m not exactly sure what the minimum requirements are, although I have heard rumours that the card must support DirectX 11.
Anyway it seems my old Radeon X600 wasn’t up to the job so I purchased a Radeon HD5450. I have no idea if it’s a good graphics card, but it’s pretty cheap and it does support DirectX 11. After installing that, IE9 was still pretty slow. Until I remembered to uncheck that checkbox…