Can confirm this issue exists in Lua 5.3.5 as well (test.lua is the same as program.lua above):
Try adding
game_field[0] ="green"
before
initialize_game_field()
and call your script with argument 1...
With that change to the above program, I get (using the same Lua on the same computer):
$ time lua test.lua 1
Array indices start with 1
real 7m38.496s
user 7m38.243s
sys 0m0.076s
Definitely seems to be an issue with assigning to index 0. 3,000 times slower is highly unexpected and should be considered a bug IMO.
