In the first demonstrations, the detection of photons with graphene was based on the pn-junction generated by the graphene-metal contact. There the active detector area is a narrow line with length determined by the contact edge and as the absorption of photons incident to a single layer of graphene is 2.3 % at highest, the detector efficiency is rather modest. However, the detector has very high speed, demonstrated up to 40 GHz and predicted to reach over 500 GHz, possibly limited only by the contact resistance.