Is there a way to change the Lego NXT sensor polling frequency?
Most sensors have the capability of sending you notifications or updates as the value of their sensor changes. This is accomplished by repeatedly contacting the NXT brick and querying the sensor. The polling frequency allows you to configure for each sensor how often this is done.
In most cases, you may leave this value set to 0, which indicates the default polling frequency. However, there may be times when you wish to get sensor reading back from one sensor more often. In this case, you can adjust the polling frequency, which is specified in milliseconds (1/1000 second).

from Device Services: Microsoft Robotics on msdn
The article goes on to suggest the range within which this can be effective.