There are no controls for the blinking behaviour (in terms of speed or fluidity) of the system caret (the text cursor to which you are referring). If it is erratic, then I would say that one possibility is that you have client-side script which is looping to the point that the browser is trying to hang. The freeing up vs. freezing up of system resources would cause the system caret to behave erratically. The other possibility is that the page content is also refreshing erratically. This, too, would cause the system caret to behave erratically.