It's a wordpress blog. I use Super WP cache.
If you are running a site that matters to you, get it onto decent hosting. That is probably going to cost a bit more but will pay back in your site actually being available.
People seem to like wpengine (http://wpengine.com) for WordPress.
If you go with some VPS hosting you could stick Varnish in front of the site, it's a while since I used WordPress but it generally seems to struggle when you are getting a lot of concurrent connections even with something like Super WP Cache. I wrote a thing for Smashing about the really basics of Varnish: http://mobile.smashingmagazine.com/2013/12/04/speed-up-your-...