If you’re into WordPress then this is a must read.
Admittedly, I have yet to try the recommended tweaks in this article though they sound promising and cover a broad range of options. There is more than using suggested plugins to analyze and speed up your site (though there are a few of those). What lends credibility is the author’s recommendation that you start with the foundation by considering your hosting company and platform. If you use cheap $4 per month shared hosting, your site will be slow regardless of any tweaks you may deploy.