Jose, he's right. A lot of browsers have trouble rendering, among other things, linear gradients efficiently. For me, the slow scrolling is apparent when you actually click and drag the scrollbar. This seems to affect Chrome, Firefox 3.6, and pretty much every browser except Firefox 4.0b7+. Firefox 4 is the first browser I've seen to render linear gradients, box shadows, and fixed elements without the "slow scrolling" performance issue.
There's not much that can be done. My own site is affected by this.
Also, I thought I'd mention, I've made some changes to the style to fix some Chrome issue if you're interested:
- Webkit has trouble rendering an inset box shadow on replaced boxes, i.e. inputs, if there is also a border-radius. To fix this in chrome, I gave the search box a regular box shadow instead of an inset.
- In Chrome, the generated "Camen Design Forum" text seems to behave strangely, shifting around in position from time to time. To fix this, I changed it from a ::before to an ::after.