arXiv:2611.09626v1 Announce Type: new Abstract: Conductance-based models are central to neurophysiology and neuromorphic engineering, yet their simulation scales poorly to large networks. We study and analyze an iterative solver that operates in signal space. Each iteration reduces to $N$ decoupled scalar linear time-varying differential equations, one per neuron, which are solved in parallel and in closed form. The solver admits two complementary interpretations: a variable metric forward-backward splitting method, rooted in operator theory, and a waveform relaxation quasi-Newton method, rooted in circuit simulation. We prove uniform and superlinear convergence, with a bound that reflects the conductance structure of the dynamics. The algorithm is illustrated on the classical Hodgkin--Huxley neuron and on networks of up to 5000 neurons.