I have heard that the new Google Caffeine algorithm is more reliant on keyword strings. Anyone have any ideas on how to best optimize sites for this "hopped up" Google?
I find that most of my sites do better with caffeine results, so I'm not too worried. You can check it here: Google Caffeine Comparisons. Seems, though, Google is weighting relevant content more with these results, so if you are writing quality articles and doing good keyword research, I think you will be happy with the change.
Page speed is a major issue it looks like. Google has added a page speed tester to Google Webmaster Tools (Labs -> Site Performance). It doesn't update often (my site was update on Dec 23rd for the overall speed metric), but it updates it suggestions weekly from the looks of it.