I don't believe it is a XenForo bug, but a Google issue. Google's +1 already has over 10 million signed up users and that number is increasing in leaps and bounds daily.
Works just fine for me, doesn't load slow, and I don't need to refresh to see it, I think Lawrence is right it was probably just something with google at the time you tried, or perhaps an addon in your browser?
More info:
The problem is specific to IE9 (9.0.8112.16421).
Tested on three different computers (Windows 7 x32 & x64) and different times.
Chrome (12.0.742.122) works fine.
I also cannot see the +1 button on any xenforo installations when browsing using my iPad. I will try adding that code Soloarquitectura has added and see what happens!
Added the code and nothing changed. I also noticed that once I did load up my forums on my iPad, I only got access to the Tweet button; no Facebook button or Google +1 so I'm not sure if I need to alter something that has been posted somewhere else on this board somewhere! I sure hope it is fixed for all browsers soon or in a future release which I have no doubt that it will be.