Caching/Content Delivery networks - In most of the internet, content is either static or dynamic. For example, Youtube as a whole is dynamic, with more content and comments etc being added daily, but the video itself, barring comments etc is static. By use of caching services like squid (done by ISP or user) or CDNs (done by ISP or site owner), you can reduce the number of connections the content has to travel, thus making it faster.
Peering - You may be using Internet Service A, but your neighbour may be using Internet Service B. So even though you are geographically nearby, in the internet, you may be miles apart if both use gateways which are far from each other - say Mumbai and Chennai. Thus, we have peering. The ISP A and B may be connected to Peering Exchange, which allows traffic from your computer to your neighbour computer flow as if they were local computers, albeit subject to some limits. This also helps if the CDN service above is connected to the same Peer Exchange, allowing you to access the services provided by the CDN at a higher speed.