Recently I've been focusing on getting linickx.com not only available, but snappy too!
- HA Proxy distributes the load across two cloud servers
- Varnish Caches have a hit rate of between 30% & 49%
- WP Super Cache serves up static files to Varnish
- HypderDB distributes MySQL Requests across my two servers
My next step is to get some minification going, either with page-speed or a WP-Plugin.. they seem to be a bit tricky to troubleshoot tho!
If you are looking to measure your websites performance, I've been using pingdom for server response times and webpagetest.org for gathering client load speeds.