why is my internet connection so low (slow)?

[BeachBro]

one day i started up my cpu, and my browser, youtube videos, and webpages took forever to load. i do not use wireless internet, i use an ethernet cable. i have a password on my router so i know my nieghbors arent leeching off. i have a ps3, also connected by an ethernet cable, that while playing call of duty, i always get kicked out of games/ can never find any due to such low internet connection. while ingame it shows that my internet is horrible and i have no clue what to do. my computer is fine, i scan it, fix any problems with it regularly. can anyone give me a solution? thanks in advance.