Increase the frequency of face detection | AWS Rekognition (StartFaceSearchCollection)

What you are referring to is addressed as latency and depends on multiple factors - the more faces to be recognized (you can create an array of faces to be checked in each frame ) the more faces the more latency will be introduced.

For example, the random landscape image’s response latency is less than 1 second, whereas calls to Amazon Rekognition for images with one face count have a response latency between 1 second and 1.5 seconds. Images with multiple face counts have a much higher response latency, greater than 1.5 seconds.