As stated AOL, Tiscalli and other bandwidth throttle specific ports and services and reduce performance at certain times of the day to cover network demands... its common practice.

Ive no idea where people get the idea that they are on a specific 'speed' broadband as nobody including AOL actually state a specific speed as performance drops with DSL the further away from the exchange you are... its the possibility which is quoted often with the words 'Up to'

In reality other than optimising the settings of your Operating System or using a better OS there is very little you can do to improve greatly

Its not uncommon for the faster packages to be actually slower in reality than cheaper packages because the 'throttling' is done on a percentage base...

http://business.timesonline.co.uk/to...cle2240380.ece

In this situation - you do not get what you pay for