Sidenote, but I'm taking a look at how googlers made this website. Reason for this is that whenever they create a webpage I can see how they've achieved an effect that people are blogging how to do efficiently. In this case the effect is the background parallax.
So... I see that they are doing this on their ideas page [1] with the following code on their background image :
So... I see that they are doing this on their ideas page [1] with the following code on their background image :
Difference from any other methods is they use position fixed and it actually looks smooth on my old mac.