If you were waiting to add the Google +1 button due to rumors about it slowing down the load time for your pages, Google has just tripled the speed. We had implemented the +1 button on several client websites, and did not see a delay time in page load (confirmed with site speed in Google Analytics). However, most of these clients have optimized code overall that does not weigh down the page with too many calls out to scripts.
If you have already implemented the +1 button, you are all set, just watch it load 3x faster!
In addition to the speed increase, Google has introduced a new “snippet” to work the asynchronous analytics code that will make the +1 button even faster. Basically, it allows your page to continue to load and appear while the browser downloads the script behind the +1 button. This way, your page does not stop loading when it hits the call to the script, they are downloaded in parallel. In order to achieve this greater speed with the async code, you will need to update your code with the new snippet. Use Google’s +1 button configuration tool to generate the +1 button code, as well as the new async code to make it even faster.