Hi Cafe, I’m glad to inform that the speed of simulation in the aivika [1] simulation library of version >= 5.2 has been dramatically increased after I started using the mwc-random [2] package for generating random numbers. It was possible to use custom random number generators before, but now the random number generator from the mentioned package is used by default. To improve the speed of simulation, in most cases it will be sufficient just to recompile your simulation models. In some my tests the speed of simulation has been increased up to 7 times when using default settings. The mwc-random package is just fantastic! Another good news is that I recently improved the distributed simulation module [3], which has recovering capabilities now in case of temporary connection errors. It should be quite unusual for the optimistic Time Warp method. In short, it means that we can build discrete event distributed simulation models using the ordinary Internet and cloud services. Best regards, David Sorokin [1] http://hackage.haskell.org/package/aivika [2] http://hackage.haskell.org/package/mwc-random [3] http://hackage.haskell.org/package/aivika-distributed