Plugins are a set of programs that adds a specific set of services to the WordPress weblog. They can extend WordPress to do almost anything imaginable.
But, inspite of this, WordPress is the slowest of all the Content Management Systems around, where speed is not only appreciated but is also highly important when it comes to improving user experience as well as for the reduction of bounce rates.
Site Speed is important for any weblog since it brings in SEO benefits and also helps in increasing consumer loyalty along with the conversion rates. W3 Total Cache, WP Smush.it, EWWW Image Optimizer, etc are a few plugins that might help with the improvement of the site speed at WordPress.