[Alan Anderson]

Are you doing the closed-loop control in the roboRIO code, and just using the Talon SRX as a way to read the encoder values? Doing that will result in some sensor lag, because the CAN communication is not instantaneous. The Talon status frames from the Talons are sent periodically. If you have enough CAN bandwidth, you can change their rate to be sent more often, which should help.