Aaron D. Campbell

There is a <a href="http://bluedogwebservices.com/problem-related-post-plugins/" rel="nofollow ugc">problem 
with related posts plugins</a>, and Efficient Related Posts is fixing that by 
approaching the problem from a different direction and offering a very different 
solution.
Basically, current related post plugins build the list of related posts on the 
fly when the user needs to view it. Since blogs tend to be viewed far more 
often than they are updated (often hundreds of times more often), these queries 
are run way more times than they need to be. This not only wastes CPU cycles, 
but if the queries are slow (which they will be if you have 1000s of posts and 
tags) then the user gets a poor experience from slow page loads.
Efficient Related Posts moves all this effort into the admin section, finding 
related posts when a post is saved rather than when the user views it. The 
advantage is that if the query is slow it happens less often and the post writer 
is the one that waits rather than the user (which I think is WAY better).
There are limitations. For example, since the related posts are stored as post 
meta data, we only store a certain number of them (10 by default, but you can 
set it to whatever you want). This means that if you decide you need to display 
more than 10, you need to have the plugin re-process all posts. I generally 
display up to 5 related posts, but store 10 just in case I decide to display 
more in some areas. Also, since the related posts are calculated when a post is 
saved, manually adding a tag through the database will have no effect on the 
related posts, although I recommend not doing that anyway.

Efficient Related Posts

A related posts plugin that works quickly even with thousands of posts and tags.  Can be added automatically to the end of posts.

wpdreams

By adding Related Posts to your content header and footer you can enhance the user experience a lot. Well designed related posts section will keep your visitors on your site for a long time.
Stop worrying about related content. Related Posts Lite will provide you a powerful and beautiful related posts solution, which works with custom post types as well. Related Posts Lite uses a complex keyword based engine to look for related content.
The powerful backend will help you to customize the layout and behaviour of the plugin quick and easy.
Why related Posts Lite?
<ul>
<li>Very easy setup, instantly works</li>
<li>Smart thumbnail images with TimThumb image library</li>
<li>Consumes less CPU power</li>
<li>Database queries are highly optimized</li>
<li>Caching lets you save even more resources</li>
<li>Solid javascript and CSS</li>
<li>Support forum is checked regulary (as you can see)</li>
<li>No limitations</li>
</ul>
Features List:
<ul>
<li>Lookup in posts, pages and custom post types (like WooCommerce products)</li>
<li>Smart fill options, if no related content is found</li>
<li>Clean sliding layout with autoplay</li>
<li>6 retina ready pre-defined themes included</li>
<li>Smart image parsing with BFIThumb image caghing technology</li>
<li>Automatic caching for better speed</li>
<li>Use the custom shortcode [wpdreams_rpl] to put it anywhere ony our site</li>
</ul>
Homepage: <a href="http://wp-dreams.com" rel="nofollow ugc">wp-dreams.com</a>
Pro version Demo: <a href="http://demo.wp-dreams.com/?product=related_posts_pro" rel="nofollow ugc">Related Posts Pro</a>
<h3>Plugin website</h3>
<pre><code>http://wp-dreams.com
</code></pre>

Efficient Related Posts vs Related Posts Lite