mysqldump slower on 5.6 ?

[Christian Richter]

hi.

i recently updated from 5.5 to 5.6
I have 500 databases to dump, about 30gigs in total.
with 5.5 i took about 11 hours to complete the dumps, with 5.6 it takes +8 hours.
what i'm doing wrong?

my backup string:
$mysqldump --user=$USER --password=$PASS --host=$SERVER --default-character-set=utf8 $datenbank > $datenbank.$(date +%Y.%m.%d).sql

read from 8 disk hardware raid and dump to single SSD

all tables are myisam

thanks