Site optimization regardless of platform will always be of some benefit to your site, Google recently decided to penalize sites that were slow loading, which will do no favors for SEO and SERPs.
It makes sense to keep your database tidy, cache files and data if possible and reduce image sizes for example.
Here are a selection of plugins that should speed up your page loads and speed things up a little in general.
WP-Optimize will cleanup the database of your WordPress install without having to use a database management software.
This plugin caches your pages and storing them in a static file, this means pageloads are much faster as well as the response time of your blog.
Wp Total Cache
Total Cache caches all aspects of your WordPress install, which improves server performance, reduces download times, decreases page load times and has a positive impact on your Google Page Speed.
WP Super Cache
This works is a similar way to WP Cache as it generates static files, most of your readers will see the static files which means it will easily handle a huge traffic boost without killing your server.
DB Cache does what it says on the tin, it basically caches every database query. It has the same kind of benefits of WP Super Cache for example, but uses less dive space that the static file cache plugins.
WP CSS Plugin
Allows you to use @import inside your CSS files and ensure it works for your readers, it also caches which allows for better server response times.
This Yoast plugin cleans, optimizes and defrags your tables within your blogs MYSQL tables, having a clean table will ensure your site is more responsive.
Google XML Sitemaps
This plugin creates an automatic XML sitemap of your blog which allows search engines to index your site, by having this information readily available for the crawlers the spend less time on your site and run more efficiently.
WP Smush It
Smush It reduces the sizes of your image files using the Smush.IT API, by optimizing, compressing and stripping meta it makes images smaller, thus they load much quicker.
jQuery Image Lazy Load WP
This plugin adds the jQuery lazyload to preload images, which basically loads images as the page scrolls, allowing image heavy sites to load much quicker and seem much more fluid.
Go forth and speed up your WordPress install, and get that page load and Google Page Speed rating way down!