Hexcore, 12 threads, 128 GB RAM but only 100+ quiz users? Your server should be able to handle many times that.
There were many recent discussions on large (1000) quiz user cases in the Hardware and performance forum: https://moodle.org/mod/forum/view.php?id=596. You should go through them and also read the main forum documentation, https://docs.moodle.org/en/Performance and https://docs.moodle.org/en/Performance_FAQ.
There were many recent discussions on large (1000) quiz user cases in the Hardware and performance forum: https://moodle.org/mod/forum/view.php?id=596. You should go through them and also read the main forum documentation, https://docs.moodle.org/en/Performance and https://docs.moodle.org/en/Performance_FAQ.