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).

Relentless Apps

RRSSB stands for ridiculously responsive social share buttons and is an adaptation of Kurt Noble’s library for web. Install the plugin and use the exposed function or shortcode to display social sharing buttons on your site.
rrssb(options);
Function options can be a string (comma separated for multiple values) 
or an array of strings
[rrssb options=””]
Shortcode options can be a string (comma separated for multiple values)

RRSSB

Create social sharing buttons using the ridiculously responsive social sharing buttons script.

DC Simple Share Buttons vs RRSSB