CoreNEURON has been developed with the goal of minimizing memory footprint and maximizing scalability on large supercomputers. It support graphics processing units (GPU), makes use of streamlined versions of data structures, and allows efficient use of compute hardware capabilities such as SIMD units on desktop as well as large supercomputing platforms. The memory usage is reduced by 7x and simulation time improved up to 6x. The CoreNEURON simulator handles spiking network simulations including gap junction coupling with the fixed time step method. This software is also part of the Human Brain Project Brain Simulation Platform.