A parallel transient simulation technique for multiphysics circuits is presented. The technique develops partitions utilizing the inherent delay present within a circuit and between physical domains. A state-variable-based circuit delay element is presented, which implements the coupling between two spatially or temporally isolated circuit partitions. A parallel delay-based iterative approach for interfacing delay-partitioned subcircuits is applied, which achieves the reasonable accuracy of nonparallel circuit simulation if both incorporate the same interblock delay. The partitioned subcircuits are distributed to different cores of a shared-memory multicore processor and solved in parallel. A multithreaded implementation of the methodology using OpenMP is presented. Examples showing superlinear speedup compared to unpartitioned single-core simulation using the direct method are presented. This paper also discusses the impact of load balancing and absolute delay on simulation speedup.