"Go is stackless where Stackless is not. Its goroutines use allocated
stacks (starting at 4k in size) and can continue running on different
threads where Stackless tasklets cannot. In fact, when a goroutine
blocks on a system call, the other goroutines in its scheduler are
migrated to another thread."
So stakcless is not really concurrent at all, given that, it is no wonder performance is different given that the functionality provided by stackless 'microthreads' is in no way comparable to goroutines.