The document Isolation function are experiencing long delay to display when access https://market.jsda.or.jp/shijyo/saiken/baibai/baisanchi/archive2020.html of xls data.
This excel file there are (10731 rows * 24 Colums) cells. The document isolation function check the cells config and display it for client so data is larger than txt data of PDF.
It takes some time to load the large object .
To avoid this long time loading.
Please add policy and document download profile your market.jsda.or.jp from your Web isolation web console such a below.
And then modify Download profile for xls and xlsx from View to Scan.