Some advice has been posted over on the SitePoint WordPress blog with some tips for speeding up the performance of your WordPress site using both internal changes and some outside testing tools.
As one of the top user experience factors, website performance is more important than ever. Website speed and performance on mobile devices is particularly important, with a rapidly growing number of visitors accessing the web via smartphones and tablets. While WordPress is very easy to get up and running, making your site speedy requires a bit more work, and is an ongoing process. In this article we'll cover why speed matters, and offer some practical advice for how to speed up WordPress. Improving performance takes a lot of trial and error, but it's great fun!
They start the post with a few reasons why speed matters to your application and its users (including higher conversion rates). The show you how to run a basic speed test using the Google PageSpeed Insights and profiling the performance using the P3 (Plugin Performance Profiler). The post then gets into some of the factors that make an impact on your site's performance including the hosting provider configuration, choice of theme and number of plugins. They recommend some simple steps like minifying assets, caching or using CDNs to host the assets and make their load faster.