For very large classes don't even try to show all the participants

user/index.php

@@ -68,6 +68,9 @@
             foreach ($students as $student) {
                 print_user($student, $course, $string);
             }
+        } else if ($numstudents > $USER_HUGE_CLASS) {
+            print_heading(get_string("toomanytoshow"));
+
         } else {  // Print one big table with abbreviated info
             $columns = array("name", "city", "country", "lastaccess");
 

user/lib.php

@@ -2,6 +2,7 @@
 
 $USER_SMALL_CLASS = 20;   // Below this is considered small
 $USER_LARGE_CLASS = 200;  // Above this is considered large
+$USER_HUGE_CLASS  = 500;  // Above this is considered too many to display
 
 /// FUNCTIONS ///////////////////////////////////////////////////////////