It's a misconception that entire internet is built with super highspeed connection between sites. However, this isn't the case. The internet is a heterogenous web of networked sites. This means that intercommunication between two different points are subject to the fastest speed of the weakest link. This is more commonly referred to as a bottleneck. Here's an example..,,
A ===== B ===== C ===== D ===== E ===== F
Let's say you're at point A and your trying to reach point F. So, lets say points A-B, B-C, D-E, and E-F are all inconnected with a 10Mbps link, but the link between C-D are a 1Mbps link. This will limit the overall speed between A and F to 1 Mbps.