Bottleneck

1. A term used to describe when too much information is coming into one source causing the computer or the device to slow down because it is receiving more information then it is capable of handling. For example, when a website is advertised on multiple different sites at the same time or on one very popular location causing an immediate increase of traffic this can easily cause a bottleneck on the web server and can cause some or all of the visitors to receive errors or very slow load times.
2. The weakest or slowest point of a program or algorithm.

Also see: Network definitions, Slashdot effect