tl;dr - Depending on whether you use Node.js or io.js, you may experience performance differ by a factor of more than 5 for identical code. [Update 21-Jan-2015: There is now a new blogpost that compares Node.js 0.11.15 and io.js 1.0.3. It also gives additional data and an explanation why io.js 1.0.2 performs so poorly in one of the tests here.] First of all, let me make something clear. This is no