Dear all, I am trying to improve my code for many cores. I have started with multicore package and the function mclapply. A multicore version of the lcapply. One problem I have is that when I use this function (you can copy and paste the below) require('multicore') returni <-function(i) {i} system.time(mclapply(seq(1:100000),returni)) I get 4 more versions of rkward.bin running (my gui is rkward). I would not care that much about that instances if each one consumed 1 GB of memory. I am not sure why this happens. Did you ever have this type of problem with mclapply? I would like to thank you in advance for your help. Regards Alex