One example: Ruby has slow IO and text-processing capabilities. I sometimes write pipeline tasks in Ruby or Perl. i.e. while line = STDIN.gets; puts transform

One example: Ruby has slow IO and text-processing capabilities. I sometimes write pipeline tasks in Ruby or Perl. i.e. while line = STDIN.gets; puts transform(line); end. Typical disk bandwidth is 2MB/s in Ruby, and 25-120MB/s in Perl, Java, Awk, or C. Beyond that, a lot of the metaprogramming features that make Ruby cool are also expensive when done repetitively. Also, Ruby's threads REALLY suck. And it has impossible to track down memory leaks in the interpreter. Ask mojombo about fun with those.