I've been giving SSBA a go to see how it does privacy- and performance-wise (as a user of one of my own plugins asked for advise on what to replace Lockerz Share with). I'm very happy to see a sharing plugin that does not include tracking.
Performance-wise it's not bad at all, but just wanted to share some ideas/ remarks to make it even better;
* by default the plugin includes Google Font, which slows the page down. Changing this to "inherit from my website" would improve the out of the box performance
* as it stands, each share service's image is fetched separately. from a performance point of view, it would make sense to use one image sprite instead.
* there are 2 issues with the share counter: 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 ajax-backend could feature some light caching (5 minutes maybe)?
keep up the good work!