Record numbers of users logging on to the web to witness the swearing in of US President Barack Obama yesterday caused an internet slowdown.

Media, news and US government sites streamed events live and prepared special sections for the inauguration, yet some were still caught off-guard and experienced performance problems.

According to Keynote Systems, an internet measurement and testing company, sites that were slow included ABC, Fox Business and the Wall Street Journal as well as those of the White House and the US Senate.

"We predicted today would be one of the most, if not the most, significant online streaming event[s]," said Shawn White, Keynote's director of external operations.

"This was an unprecedented online event. I don't think we've ever seen as many viewers go online to watch an event," he added. "It's difficult to prepare for something that's unprecedented. On a positive note, I had heard predictions that the internet would crumble, which didn't happen."

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The inauguration was the first since online video became a mainstream activity, so it wasn't a surprise that TV networks and major newspapers provided live broadcasts on their sites.

CNN, which began its web broadcast at 12pm GMT, partnered with Facebook to display 'status updates' from members of the social-networking site as they reacted to the events. According to Facebook, by 5:15pm, 600,000 status updates had been posted on Live, with 8,500 hitting at the minute President Obama began his speech.

CNN had generated more than 136 million page views as of 7:30pm, and its Live section had served up more than 21.3 million live video streams globally, setting a new daily streaming record for itself, a spokeswoman said. Live estimates it served more than 1.3 million concurrent live streams during its peak immediately prior to President Obama's inaugural address.

Content delivery specialist Akamai reported delivering record streams and content to its customer sites, such as the New York Times, Viacom and the Wall Street Journal. Akamai delivered a peak of more than 7 million simultaneous streams, most of them live, over its EdgePlatform, at approximately 4:15pm, at which time total traffic on its network surpassed more than 2TB per second (TBps). Akamai's Net Usage Index for News, a daily web traffic report of aggregate total visitors per minute to more than 100 news sites, recorded more than 5.4 million visitors per minute at approximately 3:45pm.

Other inauguration day sections could be found in Google's YouTube and Flickr. The Twitter microblogging service partnered with Al Gore's internet TV company Current TV to display messages from Twitter members online and on TV during the inauguration. However the service experienced a number of outages and delays throughout the day.

In addition to video and news articles, sites often provided other features like photo slide shows, interactive maps, opinion polls, reader comment forums and timelines.

See also: Microsoft & CNN capture Obama inauguration in 3D