Improvements over time

  rakudo-2012.01
  
  
  
  
  
  
  
  
  

Results (seconds):

              2011.01  2011.07  2012.01

while 0..^N    23.04    14.43     2.24 
for 0..^N      34.93    26.90     1.43  
startup         0.62     0.59     0.12