The SQL statement in itemgeneral.checkInput () has an SQL statement that can return a huge amount of data.

For example, when updating an item in the template with three items, linked to ~22000 hosts produces an array with 66030 elements which consume 51352040 bytes of the memory.

frontends/php/include/classes/api/services/CItemGeneral.php:575

$host_items = $this->get([
    'output' => ['itemid', 'type', 'key_', 'master_itemid', 'hostid'],
    'filter' => ['hostid' => $all_hostids],
    'preservekeys' => true
]);

SQL (2.339933): SELECT i.itemid,i.type,i.key_,i.master_itemid,i.hostid FROM items i WHERE i.type<>9 AND i.flags IN (0,4) AND (i.hostid BETWEE...

Also, this SQL statement shouldn't be executed for lld rules, since it is used for validation of dependent items and item prototypes.