Does the likes tree (on showthread) increase page load time?

I'm wanting to optimize page load time, which we know is also a factor in SEO. Does the likes tree add to page load time (as seen by the search engines, and also in real user experience)? I guess if it's loaded asynchronously (is it?) then supposedly it won't affect the page load speed in the eyes of Google. Or if it is loaded synchronously, how significant is the extra load time (as seen by search engines)?

No , it doesn't