Steps to reproduce:

1. create new test host
2. add calculated item on this host, in formula paste this value: 2500000000000000, set unit to "B"
3. go to latest data, find created item and go to graphs
4. check CPU util (top or htop) per php-fpm process, it will be 100%

Result:
frontend freezes, web-server components eat whole CPU,
Expected:
not freeze zabbix frontend with just calculated item