Essentially Google's "Caffeine" algorithm that we all know too well by now is starting to push slow websites into the supplemented results. They are not de-indexing you, just pushing you out of the way for faster websites. So what's the solution?
Deliver your website content to your user as (physically) close to them as possible so it will load fast, make them happier and make Google happier in the process.
CDN's can be expensive, especially if you run a large site with a ton of media, but there's a really cool, FREE solution out there called CORAL. If you visit their website at hxxp://coralcdn.org/ you'll find a link on the top called "Download". There you'll find a several plugins (including one for WordPress) that will automatically, or with very little effort, add your website to a FREE CDN. I've tested it for a little over a month now and I've seen noticeable improvements in my analytics. It's not a cure-all solution but it definitely gives you a little extra torque on the information highway - and I'll take anything I can get!
If you're all too familiar with CDN's then thanks for the read, if I've taught you something you don't know then I hope it works for you like it did me.