While we cannot recommend specific models, here are some general considerations:
Solving of ODE equations is inherently single-threaded. The single-threaded performance of a CPU therefore has the biggest impact on simulation speed. This is roughly equivalent with “more GHz”. Additional cores help with certain tasks, e.g. parameter sweeps or code generation.The amount of memory needed for a simulation depends on the number of scope signals, the step size and the simulation time range. For long-running simulations with many scopes more RAM is helpful. If the simulation requires more memory than physical RAM, the operating system starts swapping out memory to disk which has a big performance penalty, which can be partially compensated by using a fast SSD.Having said that, speeding up a simulation is usually a question of improving the model rather than throwing raw CPU power at it.