Public interest groups and tech companies participated in an Internet “slowdown” yesterday to raise awareness of the potential impact to net neutrality and an open Internet if slow lanes were to result from proposed FCC rules. It was not an actual throttling of Internet speeds, but a campaign in which sites featured messages about the issue and symbolic “loading” icons. Thousands of websites urged their users to take action. As a result, the FCC received a record 1,477,301 public comments.

The campaign was organized by Demand Progress, Fight for the Future, Free Press Action Fund and Engine Advocacy. According to the groups, 10,000 sites participated in the slowdown, including Digg, Dropbox, Etsy, Foursquare, Kickstarter, Mozilla, Netflix, Reddit, Tumblr, Vimeo, WordPress, and the Writers Guild of America.

In its infographic breaking down the results of the day, the Battle for the Net site claims that nearly 1.6 million emails were sent to Congress, the campaign led to more than 1.1 million Facebook shares, and there have been 4.7 million comments filed since since March 1.

“The FCC is devising a new set of net neutrality rules, but its plans stirred an outcry earlier this year as activists complained that an initial proposal wouldn’t be strong enough to prevent Internet providers from charging content companies for quicker access to the consumer, giving them an advantage over sites that can’t afford to pay,” reports Variety. “The FCC had in place a previous set of net neutrality rules, but, after a court challenge from Verizon, most were struck down by a D.C. Circuit Court in January.”

“Cable companies are famous for high prices and poor service,” reads the Battle for the Net site. “Now, they’re attacking the Internet — their one competitor and our only refuge — with plans to charge websites arbitrary fees and slow (to a crawl) any sites that won’t pay up. If they win, the Internet dies.”

Comcast, one of the cable companies criticized by the movement, responded to the campaign on Wednesday, suggesting it supports “reasonable and workable rules” for the Internet.

“Today, a few organizations and businesses who have built their success on the Internet are participating in a day of online action to demand new – and very different and, we believe, destructive – regulations in the name of preserving an open Internet,” wrote Comcast EVP David L. Cohen. “We want you to know that Comcast has no desire to break the Internet – or to do anything else to disturb its fundamental openness.”