My wow 3 lags why?

Your Details are to broad. It Depends on (1) Your Processor (2) How Much RAM you have (3) Your Graphics Card... Has it lagged before? Can your computer handle it? Can your Graphics card give the right graphics for the game?

I kinda wonder if it has anything to do with the fact that blizzard server were hacked and user information taken , the hack its self many have not much to do with lag but the work to fix the security issue could slow things down plenty if not shut them down from time to time..

lot a lots of player info was taken ..

What I would do if it is lagging. Is check to make sure that the computer that you are running is up to date with all the security patches from Microsoft. And the other thing that I would definitely check into is a speed test. With the ISP provider that you have and also compare it to speedtest.net as well to see if there is any lag from there. I had one client that her son was having major problems with lagging and found out that it was her connection that was the problem itself. She was getting like 2.3Mb/s instead of the usually 7which was the maximum she could get. Now that she had moved and gotten another ISP she is getting her full potential connection.

It's probably your system specs. These days you need a dual core and at least 2gb of RAM or better. You might try lowering the graphics settings.