Not really a howto here but more a collection of tips and tricks on MySQL
Edit the file /etc/mysql/mysql.conf.d/mysqld.cnf
And add in :
[mysqld]
performance_schema=OFF
IMPORTANT
This method is at your own risk. In case of concerns no support will be possible.
service mysql stop
rm /var/lib/mysql/ib_logfile*
touch /etc/mysql/conf.d/jeedom_my.cnf
echo "[mysqld]" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "key_buffer_size = 16M" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "thread_cache_size = 16" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "tmp_table_size = 48M" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "max_heap_table_size = 48M" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "query_cache_type =1" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "query_cache_size = 16M" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "query_cache_limit = 2M" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "query_cache_min_res_unit=3K" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "innodb_flush_method = O_DIRECT" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "innodb_flush_log_at_trx_commit = 2" >> /etc/mysql/conf.d/jeedom_my.cnf
echo "innodb_log_file_size = 32M" >> /etc/mysql/conf.d/jeedom_my.cnf
service mysql start