You may be able to overcome a sensitive gag reflex with gradual practice. In the meantime, certain techniques, such as changing your head position, may help you swallow pills or undergo dental work.
At the heart of NVIDIA's Reflex technology lays Reflex Low Latency Mode. In games that support it, you'll usually find it in the video settings, where it will be called "NVIDIA Reflex" or "NVIDIA ...