Every third party script that gets loaded on web sites when a visitor loads the page increases that page's load and rendering times.
Web browsers have made big improvements performance wise in recent times which has speed up page rendering times considerable.
The rise of social networking sites on the other hand has seen an increase in so called social media buttons on many websites.
The reason to add those buttons to web sites are simple: These buttons, if used, increase the visibility of the web site. They can also increase traffic from social media sites and decrease the site's dependency on search engines for traffic.
The biggest usability issue can also be identified easily. Only a minority of users will make use of the social media buttons to spread the post or website. The majority of users will ignore the buttons. Even though they do, they still have to load the buttons.
Users who never use social media buttons can install plugins or extensions that block those buttons on web sites. This reduces the overall bandwidth and the page loading times as the browser has to make fewer requests. In addition, they may increase the privacy of the user.
The Firefox extension Wallflower blocks both the Facebook Like and the Google Plus button on most web sites. It does so automatically and without user interaction. Most means that the standard buttons are blocked. If sites implement their own version or use plugins to display the buttons then they are still displayed.
Wallflower in this regard works like previously reviewed browser extension. This includes Widgetblock for Chrome which can block additional third party buttons or the comparable extension for Firefox, ShareMeNot.
Firefox users can download and install Wallflower from the official Firefox add-on repository. I'm currently looking for ways to only load the social media buttons on Ghacks if a user requests them. The basic idea would be to display a replacement in the position, something like Share or whatever and replace the Share link with the actual buttons if a user clicks on them. While this would mean that users who want to share need to click twice to do so, it would reduce the page loading and rendering times for the majority significantly.
Probably the biggest issue here is that Wallflower supports only Google Plus and Facebook. Since it has not been updated since 2013, it is unlikely that additional services will be supported by it in the future.