ngspice (see question), which is not (really) mutlicore feasible due to the Sparse Matrix and KLU solvers, and I'm not using a NVIDIA GPU for CUSPICE (GPU version of ngspirce). But I stopped the process anyway since I will mess around with the stimulie in GUI mode, eventually, which will also give me an understanding of the runtime. Thanks.
PS: Maybe a period of 160ns (as the default stimulie suggests) is a little bit too off for simulation, but I'll see.