We investigate the effects of input device latency and spatial jitter on 2D pointing tasks and a 3D movement. First, we characterize jitter and latency in a 3D tracking device and an optical mouse used for baseline comparison. We present an experiment based on ISO 9241-9, which measures performance of pointing devices. We added latency and jitter to the mouse and compared it to a 3D tracker. Results indicate that latency has a stronger effect on performance than small spatial jitter. A second experiment found that erratic jitter "spikes" can affect 3D movement performance.