Effective and efficient Web services infrastructures for geoprocessing are essential for fields such as e-government and e-tourism. However, few model-based approaches exist that let researchers analyze and measure system implementation performance. Here, the authors present a performance evaluation of a spatial data infrastructure (SDI) implementation based on common standards. The SDI's purpose is to compute groundwater vulnerability function. The authors study four influential performance issues: caching, network adaptation, data granularity, and communication mode.