Justin Bieber reportedly uses up 3% of all twitter infrastructure

"Would you believe that Justin Bieber and his legion of fans use up 3% of Twitter’s server infrastructure at any given time — such a large amount of activity that “racks of servers” are dedicated to Bieber mania?
So said a Twitter employee, according to web designer and blogger Dustin Curtis. Yesterday he sent out the following tweet:
“At any moment, Justin Bieber uses 3% of our infrastructure. Racks of servers are dedicated to him. – A guy who works at Twitter”
[...]
We shot an e-mail Twitter’s way to confirm, and while the Twitter rep we contacted didn’t confirm the figure, she didn’t discourage us from believing it, either. “While we don’t break out metrics like this, everything around and about Justin Bieber is consistently popular on Twitter,” she said.
Curtis also tweeted that “most of the popular users on Twitter have dedicated servers for their accounts.” He believed the Twitter employee and tweeted what he said in part because he thinks the numbers make perfect sense:
“Every time Bieber tweets, his messages have to be delivered to more than five million people who then endlessly retweet it. Apparently, his account receives more than 60 @-replies per second for a while after he tweets, which is something Twitter wasn’t originally designed to handle.”"
Source:  Dustin Curtis, reported by Mashable, 7th September 2010
Note:  It's a fun fact, but it's totally unverified.