In order to get the most out of nZEDb, you are going to have to tune the database. The default configuration will work, but if you want real speed it will take some time and tuning.

Once you have a base config, use tools such as the phpmyadmin adviser, MySQLtuner and [Tuning Primer] (https://launchpad.net/mysql-tuning-primer) to fine tune things further. Note: MySQLtuner recommends setting join_buffer_size too large.

If you are using the multi-threaded scripts it is advised to convert you tables to InnoDB to avoid table locks. There is a script under misc/testing/DB to help you with this.

Before migrating from MyISAM to InnoDB be sure to set innodb_file_per_table in my.cnf. If its too late, follow these steps to convert: Howto Clean a MySQL Storage Engine

If you're using percona you can also use https://tools.percona.com/wizard with a fresh database install. Be cautious not to check "Enable a strict SQL mode" as it will enforce ONLY_FULL_GROUP_BY which will yield in errors. It may be possible to use "Enable a strict SQL mode" with the ONLY_FULL_GROUP_BY option removed manually (added as last option to the variable sql-mode).

At the latest, once the database contains more than 1 million releases you'll need start tuning. The two queries below can provide a simple recommendation. There is also this nZEDb script

php /var/www/nZEDb/misc/testing/DB/show_table_sizes.php

SELECT CONCAT(ROUND(KBS/POWER(1024,IF(pw<0,0,IF(pw>3,0,pw)))+0.49999),
SUBSTR(' KMG',IF(pw<0,0,IF(pw>3,0,pw))+1,1)) recommended_key_buffer_size
FROM (SELECT SUM(index_length) KBS FROM information_schema.tables
WHERE engine='MyISAM' AND table_schema NOT IN ('information_schema','mysql')) A,
(SELECT 3 pw) B;

SELECT CONCAT(ROUND(KBS/POWER(1024,IF(pw<0,0,IF(pw>3,0,pw)))+0.49999),
SUBSTR(' KMG',IF(pw<0,0,IF(pw>3,0,pw))+1,1)) recommended_innodb_buffer_pool_size
FROM (SELECT SUM(index_length) KBS FROM information_schema.tables WHERE
engine='InnoDB') A,(SELECT 3 pw) B;

add to my.cnf and restart http://dev.mysql.com/doc/refman/5.6/en/innodb-performance.html

#dump/restore buffer pool, faster buffer pool warmup
innodb_buffer_pool_dump_at_shutdown = ON
innodb_buffer_pool_load_at_startup  = ON

innodb_checksum_algorithm           = crc32

Unfortunately that's about it for tuning advise. Every machine will need a different config, so don't just blindly use others. Get a base configuration for your system and fine tune it from there. There are more detailed guides out there on the net if you require further info.