#Moodle 5.0 includes a feature described as
“New #quiz attempt states and asynchronous attempt creatio”
You can read the ticket here
https://tracker.moodle.org/browse/MDL-68806
In that ticket it says
“Doing this should help greatly smooth out the two biggest peaks in server load when students are making simultaneous quiz attempts.”
I believe this will allow large scale quizzes to run with less hardware and uncertainty.