OK - I THINK I GOT THE PROBLEM -
In XLSX.pm the method new issues the following read
foreach ($member_sheet -> contents =~ /(\<.*?\/?\>|.*?(?=\<))/g) {
This is trying to cache the whole worksheet at a time; one of my worksheets in the XLSX file that is throwing the "Out of Memory" has a million rows
Is there a way I can change this to perform line by line reading?