Venerable Maria Antonia de la Paz y Figueroa, aka Mama Antula, died in 1799. Her beatification miracle occurred in 1904 and was investigated and submitted by 1905. She was finally declared a Venerable in 2010, and now her miracle has been approved in 2016.
In the old days, a simple question could take months, so they would save them all up and ship them at the same time. Then the poor folks back at home had to take months answering all the questions and then sending the answers back.
The more recent submissions are mostly electronic documents, and shipping of stuff is also faster. If the Vatican guys have a question, they can just email or call.
Of course, the real time-eater was the fact that Mama Antula wrote thousands of letters to her Jesuit friends back in Europe (and they saved them faithfully and passed them along and translated them), so the people at the Congregation had to read and evaluate thousands of letters, too!