I see few processes that run in MySql and cannot be terminated.
Looks like there is a bug in forum advanced search.

SELECT DISTINCT entityType, entityId FROM
( SELECT b.entityType, b.entityId, MATCH (b.text) AGAINST ('дата события' IN BOOLEAN MODE) as relevance
FROM ow_base_search_entity_tag a
INNER JOIN ow_base_search_entity b ON a.searchEntityId = b.id AND b.status = 'active' AND b.activated = 1 AND MATCH (b.text) AGAINST ('дата события' IN BOOLEAN MODE)
WHERE a.entityTag IN ('forum_post_public') ORDER BY b.timeStamp DESC)
result LIMIT 0, 20