Your question repeats client ID, so not sure which one actually works faster for you. But my stab at explaining it is as follows:
- Client ID returns only public photos with the tag
- Access token is user specific, so it will return all public photos as well as private photos that the user has access to (ie photos of private users that the user is following)
Since there's a little extra processing involved, it stands to reason that using access token would be a little slower, is that what you're seeing?