You could try
$(window).load(function() {
instead of
$(document).ready(function() {
so it will wait until after your images and everything has loaded.
If that doesn’t help, then I would suggest having them only appear on hover. Have a bunch of static images / CSS sprites, that get replaced when the user hovers over them.
If you don’t want that extra step, and you have server access to install modules you can try google’s mod pagespeed to defer the javascript for you
https://developers.google.com/speed/pagespeed/module/filter-js-defer
If you don’t have server access you can try the CDN route, Cloudflare’s rocket loader is very interesting, I am testing it at the minute for similar reasons, and see ~ 33% speed increase http://www.cloudflare.com/features-optimizer
If that doesn’t help you could try the old favourite of sticking the buttons at the bottom of the page and repositioning with CSS so they look higher up; that way you can have them where you want them but they don’t seem to interfere with the page load time.
You could try simpler oldschool alternatives like here http://zurb.com/article/883/small-painful-buttons-why-social-media-bu
or see if service like http://www.addthis.com/ or http://www.sharethis.com/ work any faster for you
Of course the elephant in the room at this point is that to have the 3 main social media buttons on the page, and for it to only cost you a second – sadly seems quite good! They are deceptively complicated buttons that don’t seem well optimised, google pagespeed insights finds something to complain about with all of them iirc.
Since you are taking a 100%+ speed hit, I would suggest some A/B testing to see if you really need them, i.e. for your site does being slower decrease traffic? Does having the share buttons bring in more traffic to warrant their presence?