We review work relevant to the area covered by the transmission line matrix (TLM) method, including certain historical TLM developments and design parameter sensitivity analysis for time-domain simulations. We consider exact TLM sensitivity analysis, compare it with the finite difference approach, and demonstrate its use in accelerating design optimization. We discuss ways of using space-mapping concepts for modeling and design that exploit the TLM time-domain electromagnetic simulator MEFiSTo as a fine model evaluator.