More detail please. There is an endless list of reasons why things could be lagging. How big is your model, are you in proxy or standard mode, what kind of graphics card do you have, how much memory do you have, what version of maya are you using, what is your workflow, what is your operating system, is your toaster plugged in, what is the phase of the moon.....
More info would make providing an answer easier.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 12-08-2011 at 07:29 AM.