A 200 MB text file will contain about two million text lines. There is no point in creating a table with two million rows, no-one will ever scroll through all of them.

You can read the file, and then display only the first e.g. 1000 lines that match your search criterium.

Or you could write a datamodel class for your text file, and then use a QTableView widget, and the view will request only the data for the rows that need to be displayed. But I don't know how much about this, so I don't know if it is easy to do.

Best regards,
Marc