bigfile1.xls 10,379,264 # Original from Spreadsheet::WriteExcel. 100% bigfile2.xls 10,525,184 # Resaved by Excel in xls format. 102% bigfile3.xlsx 2,733,546 # Resaved by Excel in xlsx format. 27% bigfile4.xlsx 2,325,559 # Original from Excel::Writer::XLSX. 23% bigfile5.zip 1,888,573 # bigfile1.xls zipped for comparison. 18%