This study reports the high-speed performance of 850 nm oxide-confined vertical cavity surface emitting lasers (VCSELs) with a planar process and reduced parasitic capacitance. The parasitic capacitance of VCSELs was reduced using additional proton implantation. The small signal modulation bandwidth which was restricted by electric parasitic capacitance expanded from 2.3 GHz to 9 GHz after proton implantation. The reflection coefficient showed that the electric parasitic pole exceeded 20 GHz. An eye diagram of VCSEL with reduced parasitic capacitance operating at 10 Gps with 6 mA bias and 6 dB extinction ratio showed a very clean eye with a jitter of less than 20 ps.