2004 Honda Civic speedometer problems

My speedometer doesn't like to work when it is cold. It will bounce for a second when you first start going, but then even if you get on the freeway it just sits at 0. If you drive for an hour or maybe even 45 min. And then come to a complete stop it sometimes will work. And sometimes after it is warm it will bounce for a few minutes and then when you get upto freeway speeds it will say you are going 20 when I know I am going around 80. Does this model have a cable or is it electronic? Is the cable maybe snapped in the middle? Should I just start car shopping:):):):):):)