No tracking and performance isn’t shabby either, but some speed-improvements could be made:
By default the plugin includes a Google Font, which slows the page down. Changing this to “inherit from my website” in the “Styling”-settings, improves the performance.
Each share service’s image is fetched separately, from a performance point of view it would make sense to use one image sprite instead.
You can add a share counter: but without a caching plugin the page load is slowed down significantly, but with a caching plugin the counters aren’t updated any more. ideally the share counter would be empty on page load (i.e. just placeholders in HTML) and after the page has loaded an ajax call would get and set the correct numbers. The “backend” the ajax-call connects with could feature some light caching (5 minutes maybe)?
Doing Web Performance can be so easy, really! I was asked to do a performance analysis of a new website and one of the things I didn’t like was the fact that the footer contained social media sharing buttons using the ShareThis widget. I’m not a fan of sharing widgets in general, as they tend to slow webpage loading and rendering down and as they almost invariably come with “3rd party tracking” for behavioral marketing purposes.
Conclusion: if performance is of any importance for your website (and it should be), you really have to avoid using 3rd party widgetery!