hi
in the messaging page, under https://demo.moodle.net/message/index.php?viewing=search for example.
there is an option to search for "Messages" or "Contacts".
if you choose "Contacts" and enter one letter, for example "a", it will search a user that has "a" in it's full name without limit.
this means that if you have 9000 users, and 6000 of them have "a" in their name - it will show you 6000 results and crash your browser.
we have more than 9000 users.
and there anything that can be done to prevent the user from making such a search?