Drilling and well-completion costs can amount to around 70-90% of the total cost of geothermal power plants, as wellbores need to be drilled to depths of several kilometers, where rock temperatures can reach 150 °C and more. Plasma-Pulse Geo-Drilling (PPGD), among other abrasion-less drilling methods, has the potential to significantly reduce these drilling costs, as the absence of mechanical abrasion significantly reduces drillbit wear and, thus, tripping time. While several studies have shown that PPGD can outperform mechanical rotary drilling under ambient pressure and temperature conditions, the impact of deep wellbore conditions with large temperatures and hydrostatic and lithostatic pressures is rarely studied for PPGD. This is also necessary to assess the economic feasibility of PPGD for geothermal well drilling or similar applications in crystalline rocks. Previously, we investigated the impact of temperature on the performance of PPGD in granitic rock. In this work, we continue this line of research by introducing and employing an experiment protocol to run experiments to investigate the impact of lithostatic pressures of up to 150 MPa, corresponding to 5.7 km depth, on PPGD performance. To quantify PPGD performance, we investigate the following two metrics: (1) PPGD productivity, defined as the rock volume excavated per electric pulse, and (2) specific energy, defined as the energy required to excavate a unit volume of rock. In addition, we combine the findings of this work and those in our previous work on the impact of temperature on PPGD performance to shed light on the effect of depth on the performance of PPGD.