what is ur ping? what is ur average ping on other FPS? what is ur isp? try going to the command prompt (in start/programfiles/accesories/command prompt) and type in after C:/>ping (web site or ip adress like yahoo.com) -t
another problem could be that the servers u are connecting to are far form you or u have to take many hops to get to them? where do u live? u could ask were the certin servers are that u connect to. there are many things u need to investigate and find out to try and solve your problem but im sure its not the game, reinstalling will not fix the game. nor will redownloading. and make usre u hae no programs running in the background using ur connection.(u can do that by pressing alt+ctrl+del) and looking to see what is ruinning, dpends on teh operating system of corse.