For non-spiking neurons, this means not larger than 100 usec for a reasonable degree of accuracy. With cables broken into compartments of 0.01 lambda a simulation using relaxation runs slowly, but with compartments of 0.1 lambda it is competitive with Gaussian elimination. This seems reasonable, because for a simulator based on compartments, how long it takes to solve a compartment might seem at first glance to be a basic and very useful measure. However, there is a problem with this definition of speed. This is misleading because not all compartments are equal in their effect on the simulation.
Compartment size is a major factor in the quality of simulation.
Smaller compartments give more spatial accuracy, and larger ones allow the simulation to run faster. The number of compartments required to simulate a neural circuit varies inversely with the compartment size. Therefore the speed of a simulator at running the simulation is not always directly proportional to its speed in solving compartments. On the contrary, it is imperative that a compartmental simulator be efficient at solving the difference equations that represent compartments. However, the time it takes to solve a compartment is not really at issue.