Here some 1.9 mingw results http://pastie.org/752318 ruby 1.8.6 mingw: GoogleHashSparse 0.625 (populate) 0.546875(each) GoogleHashDense 0.234375(populate) 0.421875(each) Hash 0.5 (populate) 0.53125 (each) 1.9.2 linux: GoogleHashSparse 0.3342118263244629 (populate) 0.05078697204589844 (each) GoogleHashDense 0.14588713645935059 (populate) 0.056185007095336914 (each) Hash 0.34199094772338867 (populate) 0.8924679756164551 (each) 1.8.6 linux: GoogleHashSparse 0.305501222610474 (populate) 0.78859806060791 (each) GoogleHashDense 0.161197900772095 (populate) 0.810173988342285 (each) Hash 0.269010782241821 (populate) 1.00644612312317 (each)