Speed of Sight?

[Edenstar]

The Basilisk in Harry Potter is one example of several characters whose primary means of attack is the simple act of visual contact. But what attack speed would this theoretically give them; what is the speed of sight - or rather, sight-based abilities, that activate "instantly" upon visual contact? Is it subsonic (the limit for faster-than-eye movement according to the speed page), is it the speed of light, or somewhere in-between?

 

[CNBA3]

from what I understand, Speed of sight is the speed that you perceive a image.

 

[Antoniofer]

Generally Perception Speed (sight perception to be more accurate), performing an action that simply people is unable to see (like, one frame is ther eand the next one is not) then it can be said that the action took more than 60-220 Hz (don't remeber what it was right now, but is within that range).