Don Caprio

As the name implies, this social sharing plugin is simple and loads pretty fast. The buttons do not rely on external resources to load, it’s written in PHP, HTML and CSS.
There’s an option to show the buttons on posts and pages. You can also put the buttons anywhere in your template using this template tag:
<pre><code><?php dc_social_share_tag(); ?>
</code></pre>
You can also display using this shortcode in single posts and pages:
<pre><code>[dc-social]
</code></pre>
Please note that these buttons do not show share counts. The essence of the whole thing is to keep it very simplified.
The only button that requires a little snippet of JS to work is the Pinterest button but this does not slow down your site in anyway. A demo of the plugin can be seen here: http://geek.ng/

DC Simple Share Buttons

A set of very simple social sharing buttons that loads pretty fast (no javascript, no images).

Ruven

This plugin provides a function to output links to share a post to Facebook, Twitter, and Google+.
Selected themes by Ruven will display the links automatically when the plugin is activated. 
In other themes you will have to edit the templates in your theme in order to output the links.
Here an example of outputting the links in as list:
<pre><code><?php
if(function_exists('ruven_sharing_links')) {
 echo '<ul class="sharing-list">';
 $sharing_links = ruven_sharing_links();
 foreach($sharing_links as $sharing_link) {
 echo "<li>$sharing_link</li>";
 }
 echo '</ul>';
}
?>
</code></pre>
<h4>Usage</h4>
<pre><code>$sharing_links = ruven_sharing_links( $get_array, $include, $open_in_new_tab, $class );
</code></pre>
<h4>Parameters</h4>
$get_array 
(bool) (optional) If you want the return value to be an associative array (title, URL) or an array of HTML links. By getting an associative array, you are able to customize the output more.
Default: false
$include 
(array) (optional) If you don’t want all platforms (Facebook, Twitter, and Google+) included, you can specify here which you want specifically to be returned. E.g. <code>array('Twitter', 'Facebook')</code> would only return Twitter and Facebook links.
Default: array()
$open_in_new_tab 
(bool) (optional) If you want the sharing dialog to be opened in a new tab/window or not.
Default: true
$class 
(array) (optional) Classes you want to add to the links. E.g. <code>array('sharing-button', 'big-button')</code>
Default: array()
<h4>Return Value</h4>
If the value of <code>$get_array</code> is <code>false</code> (default), the function returns an array of HTML links.
If the value of <code>$get_array</code> is <code>true</code>, the function returns an associative array of the title (e.g. “Twitter”) and the URL to share the post.

Ruven Themes: Sharing Links

RT Sharing Links provides a function to output links to share a post to Facebook, Twitter, and Google+.

DC Simple Share Buttons vs Ruven Themes: Sharing Links