iambic9 - 9:51 am on Jul 30, 2010 (gmt 0)
Don't be Google's puppet
I couldn't agree more with the above, if you're primarily motivated by anything other than giving your users the best experience possible, then I'd argue that "Site Performance" (as measured by Google) is the least of your problems. I'm completely obsessed with UI design and user experience. Not a single thing is more important than the experience a user has when then arrive on your site.
Something I've been experimenting with recently is preloading content based on the path a user is most likely to take through our site.
Now this can be as simple or as complicated as you'd like to make it, if your site structure and content is well managed, a users next click should be – with some degree of accuracy – predictable, and if you know where your user is going next, you're missing an opportunity to improve usability if you're not getting that content ready for them before they arrive.
OPTIMISED LANDING PAGES
During the 30 second user ponder, I start preloading the master CSS for the site, a small JS library, a CSS Sprite and the main image for the significantly fatter linked page. The result is a home page that loads incredibly fast, and the second click from the user pretty much just snaps into place, it's particularly impressive for the user because the image on the second page is usually 850 x 500 and it appears in under a second, the user has no idea that they are preloading our content in bite size chunks and just assume it's quick.
YMMV, this practice works well for us because we use a lot of large glossy images of products that have an emphasis on design, and we spend a lot of time looking at user data so we're pretty clear on what to preload and what not to. Of course now and again you're going to load content the user doesn't need, but it's a small price to pay if you can afford it.