Website loading speed is said to be a factor in determining SERPS order. Is it true?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Carl Harvey: Good question as i have them on my site...It will be interesting to hear what people think
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  Morten Pedersen: Yes good question. I just did remove my widget and replaced them with just images to Face/G+/Twitter for getting better speed.
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  Arseniy Bolotsko: You can split the baby in half. Cut down the amount of buttons you use. If you have a blog page that has 20 blog summaries on it don't include social stuff. Only include them on the page which has the articles itself.
  
  Also, with some basic html/css/php you can manually install the buttons. Take out all of the extra junk that is in the plug-in.
  
  One time, I reduced the load time of a page dramatically by changing Twitter url from https to http. Problem was that the secure url was taking too long to authenticate. Took me an hour to find the problem and 1 second to fix it.
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  Andrei Gherghel: Use the async version of the java scripts, available for G+, Facebook and Twitter. It will look like the page takes longer to load since the scripts will load the widgets after the initial page is fully loaded. 
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  Unique Websites: +Arseniy Bolotsko ;thanks for the tip about https - hadn't thought of that. The tip about manually loading buttons could be good too, although that limits the systems that your content might be shared to.
  
  However, with regards to buttons like AddThis that load AFTER the rest of the page, does your site get marked down because they add to the total loading time or is Google smart enough to realise that this doesn't interfere with visitor experience?