Looks like PCRE regexps use much more CPU resources than regexp in previous zabbix versions!
We use regexps like
in trigger and its a trouble.
When we change the trigger expression to evaluate value 4 times by str() function, it helped, but it's a workaround and still cannot be used for all cases.
This should be investigated and addressed.
There is also suggestion to move to pcre2 in ZBXNEXT-4922, it potentially might help.