According to the web analytics company the Twitter's rate of growth in signing up new users started dropping dramatically last autumn.
HubSpot said in its latest 'State of the Twittersphere' report that while Twitter had grown very rapidly over the past couple of years the growth rate dropped to 3.5 percent in October compared to 13 percent just seven months earlier.
The report did note, however, that a recent study of Twitter users found that they are becoming... well, better Twitterers.
The average Twitter user today follows substantially more people, is followed by many more people, and posts more updates than he did in mid-2009, according to HubSpot.
For example, last July, the average user had about 60 followers; by January 2010, that number had jumped to 300.
"The change may be a reflection of the slowing growth rate," the report said.
"Because of the slowing growth, today's population of Twitter users has been using the tool longer than the population several months ago ... experienced users make up a larger portion of the population."
But Twitter users who feel badly that they don't have massive numbers of followers like Twitter giants Ashton Kutcher and Oprah Winfrey can take heart in the fact that 82 percent of their fellow tweeters have fewer than 100 followers.
The analytics firm also noted that Twitter users are night owls; the hour between 10 and 11pm is the most active period of time on the site.
The study was based on analysis of five million Twitter profiles and six million tweets.