In version 7.0, if User Groups use “Problem tag Filter” like this:

Users experience a very high load time, around 30 seconds, this makes the Problems page unusable.
One way to fix problem of creating these two indexes on database Maria DB 10.5:

create index items_11 on items (itemid,hostid,key_(100));
create index functions_4 on functions (triggerid,itemid);

After the creation of these two indexes, the load time passed from 30 seconds to 0.5 seconds.

Similar benefit happens on Zabbix 6.0, where the outcome is 1.9 (without) VS 0.3 (with) seconds.

In Addition to that I see that with version 7 , a lot of TMP table are created on disk by MariaDB , so we need to increase the tmp-table-size parameter to 4GB .

Size stats about tables sizes: zabbix7db-size.txt