According to David Martin, Vice President of Primary Research at Internet traffic monitor Nielsen Online, the site suffers from a retention problem. From month to month, Nielsen data says, just 40 percent of Twitter's users return to it.
The microblogging service has been tech darling of late, racking up new users at a dizzying pace. When daytime diva Oprah became a user live on her TV show earlier this month, the site saw a 43 percent increase in traffic, Hitwise reported.
But the Oprah crowd – and thousands of new users like them – aren't coming back nearly as often as they need to be if Twitter's growth is to be sustained, writes Martin.
"There simply aren't enough new users to make up for defecting ones after a certain point," Martin says in his blog post.