In ZBXNEXT-413, Timer process codes are modified. especially for tag based maintenance. Now I check them.
The following code is In the function db_get_query_events().

226 result = DBselect("select eventid,objectid,r_eventid"
227 " from problem"
228 " where source=%d"
229 " and object=%d"
230 " and " ZBX_SQL_MOD(eventid, %d) "=%d"
231 " order by eventid",
232 EVENT_SOURCE_TRIGGERS, EVENT_OBJECT_TRIGGER, CONFIG_TIMER_FORKS, process_num - 1);
233
234 while (NULL != (row = DBfetch(result)))
235

{ 236 query = (zbx_event_suppress_query_t *)zbx_malloc(NULL, sizeof(zbx_event_suppress_query_t)); 237 ZBX_STR2UINT64(query->eventid, row[0]); 238 ZBX_STR2UINT64(query->triggerid, row[1]); 239 ZBX_DBROW2UINT64(query->r_eventid, row[2]); 240 zbx_vector_uint64_create(&query->functionids); 241 zbx_vector_ptr_create(&query->tags); 242 zbx_vector_uint64_pair_create(&query->maintenances); 243 zbx_vector_ptr_append(event_queries, query); 244 }

245 DBfree_result(result);

I think that it occurs bad performance for many problems remaing.