depends, on what is causing your lag really. could be a number of factors, your using too much bandwith ie running other programs in the background, viruses/spyware/adware, your on a network with other people who are browsing lots of webpages... the list goes on really
Whats your connection speed?
Are you in a LAN? (Local Area Network)
Have you scanned your PC recently for any intruder programs?
Are you running more than one internet based program on your PC at a time? (this is negligable though as some connections can handle a vast amount of internet traffic)