According to an FCC study, high speed internet providers advertise speeds 50% higher than what they actually deliver. The study states it is because of end-user limitations, congestion, network quality and bandwidth distribution. In other words, during peak hours (hours in which the most people are online) speeds lag as more and more information is sent over the network. This isn't a new finding. The New York Times ran an article on the situation as early as 2006. A United Kingdom consumer watchdog administered a similar study in 2007 and found that internet speeds were about 1/3 advertised speeds. Techdirt has condemned the practice for more than 6 years.
Advertised broadband speeds are inherently misleading because they use the words "up to." When advertisements boast super-boosted-turbo speeds of "up to 15mbps" the speeds actually fluxuate wildly. Because the only information on which consumers can base their purchases is "15mbps," they often believe those are the speeds they will receive (most of the time) when they are on the internet. This is not true at all. During peak hours--from about 5p.m. to 11p.m.--speeds drop exponentially as people home from work stream videos, hop on Call of Duty: Black Ops or download music. People rarely see the advertised speeds while they are online.
In some congested areas, as with Downtown Kansas City, over-utilization of cable networks will slow broadband speeds to a crawl. It makes it impossible to finish a Youtube video without the loading bar stalling. Cable companies invariably blame the problems on the consumer's home network or the modem, but they often are not the problem. The City of Los Angeles got sick of lousy service and sued Time Warner. Several more Californian customers felt they were deceived by ads claiming speeds "up to" a certain amount and sued Hughes Communications for not providing service anywhere near the advertised speeds. The consumers won. Australian authorities got sick of the misleading advertising and told broadband providers to knock it off.
If you feel you are not getting the internet speeds you pay for, you can test your speeds at such sites as www.speedtest.net or www.speakeasy.net. If your broadband speeds are far below what you pay for, contact your provider. If they are unable or unwilling to address the problem, you can file a complaint with your local BBB or consumer protection division such as your state Attorney General.