In this paper, we expand on previous work in which we investigated algorithms and cost functions for dense OPC. We explore using multiple contours at different process conditions in order to generate "process window OPC". We analyze and discuss the computational cost of the dense OPC approach in comparison to sparse OPC. We also discuss the flexibility to use any possible resist model inside a dense OPC system. We show how the dense OPC system can be used together with dense, contour-based verification for the 45nm node. The dense verification and OPC tools provide a framework for lithography friendly design and DFM for the 45nm manufacturing node.