If your computer lags in one place and not in another, it may be due to the way Wizard101 handles locating quest targets (my term), in other words, the "quest arrow" or "quest helper", while the player is moving. Fortunately, this only happens in a few limited areas (there's a whole area of Mooshu that it can happen in), and only for certain computers.
One possible solution is to turn the quest arrow off. You can do turn it off and on by pressing "T" on the keyboard.
If doing this doesn't help, then it's something else, and you should send in a ticket to Support.
If turning off the quest arrow removes the lag, then you can still use the quest arrow, but it will take a bit more work. The lag will only happen when you're moving. To use the quest arrow in lag areas, you should stop moving, turn the arrow on ("T"), check the direction and distance needed, turn the arrow back off ("T"), and move on. You can stop and go this way until you find what you want.
When you leave an area, you can test the lag again by turning the quest arrow back on and moving. The lag issue only happens for certain areas.