$ /opt/cperl-5.24.3c/bin/cperl -I. tbench1.pl x.tmp 2
cell count at start = 1500000
run benchmark for 2 ticks
cell count at end = 1500000
time taken: 116 secs   - infinite board
time taken: 163 secs   - original
time taken:  54 secs   - improvements
time taken:  36 secs   - optimized pack i2
time taken:  37 secs   - two numbers into one
time taken:  37 secs   - shorter implementation