I’ve tried many social plugins in different formats, but the one I am very exited now is the Floating share bar.
It was introduced to me by a friend who collects the best WordPress plugins.
Digg Digg is one of the best free floating share bar plugin, created by Buffer.
Your site will display all social sharing buttons, just like Mashable.
One of the features is the choice for Lazy loading to increase website performance.
With more than 650,000 downloads You shoud take a tour here
They also take suggestions from users for their next update.