Simulator efficiency. Test system simulation runtimes in STEPS, MesoRD and Smoldyn. Filled circles show points where the simulation is calculated to be accurate and open circles show where simulation may be inaccurate. A. Low number of molecules initial condition. Left panel: STEPS and MesoRD simulation runtimes at different number of subvolumes describing the same total mesh volume. Right panel: Smoldyn runtimes with varying number of simulation iterations due to a change in time-step. B. High number of molecules initial condition, which is the only difference from simulations shown in A. Notice different y-scale between A and B but not between left panels and right panels.