Niteo

Spider Blocker blocks most common bots that consume bandwidth and slow down your blog. 
It accomplishes this by using .htaccess file to minimize impact on your website. It’s hidden from external scanners.
Spider Blocker is specifically designed for Apache servers with mod_rewrite enabled, allowing you to effortlessly safeguard your website from the most prevalent bots that hamper performance and drain resources.
<h4>Plugin Features</h4>
<ul>
<li>Block Unlimited bots from viewing your site</li>
<li>Easy Export/Import rules (comes with most common list of bots)</li>
<li>Zero Footprint</li>
</ul>

Spider Blocker

Does what it promises to do. No more bad bots to my WP blog :)

Perfect!

SpiderBlocker will block most common bots that consume bandwidth and slow down your blog.

kaggdesign

PageSpeed Module is an open-source module for Apache and Nginx created by Google to help Make the Web Faster by rewriting web pages to reduce latency and bandwidth.
The plugin allows purge caches created by Apache or Nginx Module and turn on development mode for WordPress site, bypassing PageSpeed cache.
The plugin requires PageSpeed Module to be installed with your Apache or Nginx web server. If PageSpeed Module is not installed, the plugin does nothing.

PageSpeed Module

You saved me the job of developing a plugin! Thank you.

Does what it says on the tin

PageSpeed Module plugin supports WordPress installation under Apache or Nginx with PageSpeed Module.

Spider Blocker vs PageSpeed Module