According to the network security firm, in March 2007 the social network accounted for hardly any internet traffic but its popularity in three years has surged.
Arbor Networks also said this figure excludes traffic through what are known as content delivery networks (CDNs) such as Akamai, so the true number could be higher still.
In short, Facebook is now an internet giant on a scale exceeded by only companies such as Google, another player whose traffic rise Arbor has charted in recent times.
Strikingly, Facebook's rise is paralleled almost exactly by a 'zero sum' decline in rival MySpace, which has plummeted from traffic peaks of up to 0.6 percent of all internet traffic in 2008 to today's sub-0.1 percent figure.
Facebook's traffic needs are now believed to be the equivalent of more than 30,000 servers.
The graph published by Arbor makes stark reading not only for MySpace but for all other social networks that hope to carve a niche in the English-speaking world and beyond.
"While Facebook may not yet have the same infrastructure footprint as Google or other larger Hyper Giants, the game is clearly afoot. Leveraging wholesale datacenters, third-party CDNs and a raft of partnerships and alliances, Facebook may yet outgrow competitors with an all encompassing social media cum application platform," says Arbor's stat guru, Craig Labovitz.
Arbor has published a series of traffic analyses that give a fascinating insight into what is really happening on the internet right now, particularly regarding the rise of supergiant, Google.
The internet has always been seen as being in a state of permanent flux, but it also appears that traffic levels in some way now speak of internet power and this is shifting inexorably towards fewer and fewer super-companies.
The internet could have embarked on the defining period in its history that will rub out some well-known names.