While there is little doubt that Google is heavily invested in its still very young social network Google+, there has also been the general feeling that this early rush of traffic to the site wouldn’t last forever. This seems to be backed up by figures, reported on by Bloomberg, that show traffic to the fledgling site falling off last week in the US. Update with statement from Google below.

The statistics come by way of Experian Hitwise, a web stats and tracking firm. According to the report, the total visits to Google+ amounted to 1.79 million in the U.S., a 3% decline over the previous week. This is a tiny reversal in traffic growth from the 283% growth that Google+ saw the week before that. In addition, less time was spent on the site per user, falling 10% to just over 5 minutes, said Hitwise.

These statistics indicate that traffic to Google+ may be flattening out after an initial adoption rush driven by the early adopters and the simulated scarcity of invitations caused by the slow release of slots for new users. After Google+ gained 10 million users in two weeks, it almost seems like any normal amount of users might feel slow.

Google+ earned itself some hot water last week over the use of pseudonyms in place of real names on the site, although some have found ways around the naming policy. Google+ has had a generally positive reception among the early adopters of the service, with many praising the design of the Circles feature, the development of which was led by Mac software designer Andy Hertzfeld.

Once the service becomes widely available to everyone and it launches its profiles for businesses, we should definitely see another uptick. It will be interesting to see if Google+ gains enough of a toehold outside of the early adoption crowd to maintain its status as a major contender in the social space.

If you’re using Google+, does it feel slower to you or faster than ever? Since these numbers only cover traffic in the US, we wonder if the numbers in other countries show similar trends.

Update: We spoke with Google about the above report and the company said that there are several reasons why this data may not be telling the whole story with regards to Google+ traffic. While the traffic numbers gathered by firms like Hitwise may be accurate, they do have limitations in what they can track.

For one, they can only track visitors to the Google+ homepage and sites that refer to it, which means that they may have been tracking people who were visiting the homepage only to find that registrations were closed and then leaving. The traffic from these visitors has most likely seen a natural waning since the announcement of Google+, but that doesn’t mean that actual users of the network have experienced the same drop off.

As far as the amount of time spent on the site, Google says that there are two important metrics that aren’t being considered. The first is mobile traffic from the iPhone, Android and mobile web apps, which it says contributes significantly to Google+ traffic.

The other is the navigation bar that is now present across Google properties. There is a notification button there that allows users of the network to engage, comment and perform other actions, none of which is being tracked.

Many of these statistics can only be measured internally by Google itself. We asked when internal measurements might be made available and it said that official numbers may be released, but that it was waiting to get metrics that reflected normalized traffic beyond the initial rush before it did so.