In an oddly fortunate coincidence, I switched PortableApps.com to using custom static social sharing buttons yesterday afternoon to speed the site up. It's worked very well.
The only tradeoff is losing the Facebook like button (which is kind of useless on web pages these days anyway) and the like/tweet counts. The upside is lightning-fast loading (just image links) as well as increased privacy for your visitors. The buttons use a single Javascript function to bring up a centered window about the size of the standard social sharing widgets using the sharing URL so the functionality is about the same.
It isn't an entirely new idea as I've seen a few different writeups on it online. My solution is based on ideas from a few different online sources as well as my own custom images and tweaks. I'm planning on implementing it as a standard Drupal module posted on Drupal.org for my own sites and including options for faded and grayscale buttons to better blend with alternate themes and not grab too much attention from content. I could probably put together a quick set of code and throw it on Github as well if people are interested in just using the raw code or working up a WordPress module for it.