Attempting to cite `ps`, which includes the unique pages as well as <i>all shared pages</i> used by the process--i.e. pages created by its parent to store such trivialities as the entirety of the Ruby runtime and the classes loaded therein--makes me question your understanding of the Linux process and memory model. Do you understand how fork(2) works on a modern Linux machine with regard to memory page sharing from parent to child? Suffice to say that nobody running a hojillion processes in Unicorn or another forking process worker--and I should point out that I have written one of these in Ruby, this isn&#x27;t Unicorn magic--is suffering under the tyranny of large amounts of duplicated data. (I&#x27;m sure there are people who spin up X of a process from the jump, but they are swimming upstream and are not the norm in my experience.)<p>The difference in memory usage between a forked process on a shared-page&#x2F;copy-on-write OS and a thread is <i>infinitesmal</i>. You&#x27;d have better luck arguing about having a JIT and better perf (and there you&#x27;d be incontrovertibly correct, but I don&#x27;t think it really matters for 95% of everything).