Victor Reyes schrieb: [...] > ruby -v > ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32] > > *Ruby: > ruby sudoku01final.rb > Elapsed Time: 0.437 Secs* > > jruby -v > ruby 1.8.6 (2008-05-28 rev 6586) [x86-jruby1.1.2] > *JRuby: > jruby sudoku01final.rb > Elapsed Time: 1.058 Secs* jruby has certainly higher startup costs than native Ruby, but that does not mean its overall performance is bad. I suggest you modify the program so it runs for example 10 times and then run again. I am sure the JRuby program will be very much below 10s bye Jochen