The site launched a stripped-down version called Facebook Lite in August in a bid to enable internet users in countries with slower broadband speeds such as China to sign up.
By comparison, Facebook piled on traffic between February and May, with unique monthly users increasing 53 per cent to 113,014,638.
Traditionally, internet traffic tails off in the summer months; however, the expected bump in traffic did not occur for Facebook in September as people returned to work.
Twitter also experienced modest growth during the summer months, with monthly unique visitors undergoing only marginal growth, up 2.4 per cent from May figures to 23.5 million unique users in September.
In September, Facebook and The Nielsen Company joined forces to offer greater measurement of Facebook ads via a service called Nielsen BrandLift.