Crawl 100 slow spreadsheets from Interent

A spreadsheet is a Microsoft Excel file (eg, .xls .xlsx or .xlsm files). I am interested in "slow" spreadsheets, which means a re-calculation of all its formulas takes more than 5 seconds. They are often quite big in size and complex in structure. They may or may not contain VBA macros. I would like to collect slow spreadsheets as many as possible (say 100) to evaluate a analysis tool myself. One way is then to scrap them from Internet. As Excel files on the Internet are often small (and fast). This process consists in crawling a lot of Excel files and filter those are slow (by VBA code, which are not very complex). Let's say, I guess from 1000 randomly downloaded spreadsheets from Internet, there may be 1 that is slow enough? To conclude, as the result of the project, I would like to have 100 slow spreadsheets, and all the scraping and selecting code to achieve this.