but probably a premature and ill considered 'optimization'

If the size of the dataset is sufficient to make re-using the original array worthwhile, then you could just the subarray back over the string from which it was derived:

$_ = [ $name, $rrate, $wrate, $total ];
[download]

That would allow the space used for the original strings to be reclaimed and reused.

Given that source of the data is only 2MB, that probably isn't a worthwhile consideration though.