Steps to reproduce:

1. create Zabbix installation with a lot of hosts linked to templates (for example, 50000 hosts, each host linked to 5 templates, 250000 hosts_templates records)
2. execute API call host.massadd with parameters

   {
     "hosts": [
       {"hostid": 149105}
     ],
     "templates_link": [
       {"templateid": 149109}
     ]
   }

Result:
The current implementation of this check consumes ~0.35 seconds and ~60 MB of memory.