The Nintendo Switch console responds slowly when it's in TV mode or the TV sound is out of sync.
When you use a Nintendo Switch console in TV mode, the console sends information to the TV, which is then output as sounds and images. The sounds and images may be out of sync depending on what the console is doing, but this should not be considered a defect.
Your TV may have a "game mode" or some other feature in which the internal processing speed is increased. Using this mode may resolve the issue of the sound and image being out of sync.