That cause VERY high upload traffic, and VERY high server load.
BTW!
EXPLAIN SELECT `leaf` , `timestamp`
FROM u43471.freechat
WHERE `server` = 'a7cadd6352026d04d4133315cc20deaf'
AND `group` = 'channelid-to-msg'
AND `subgroup` = 'ch_%D0%92%D1%81%D0%B5'
GROUP BY `leaf`
ORDER BY timestamp
1 SIMPLE freechat ref PRIMARY PRIMARY 606 const,const,const 16 Using where; Using temporary; Using filesort
do you see "Using temporary" and "Using filesort" ??
That also cause VERY HIGH mysql load
