Too long sql request on web hosting server

Hello NGG users & staff

I’ve received few days ago a mail from my shared web hosting (Infomaniak)

It seems that certain requests SQL of your xxxxx.com site are not sufficiently optimized and involve an overconsumption of resources on the MySQL servers.
In occurrence, the server indicates a 830 seconds total for only 130 requests.
Time execution seems too important
– it misses one or more index on the tables used in the request
– the request is badly written and examines an incoherent number of lines
– the type of the fields used in the tables are inappropriate (varchar instead of int, etc)
– etc

here is the bad request log

# Time: 140302 20:48:22
# User@Host: xxx13[xxxx] @ imu249.infomaniak.ch [xx.xx.xxx.254]
# Query_time: 54  Lock_time: 0  Rows_sent: 1  Rows_examined: 3316754
use xxx13com;
SELECT wp_ngg_pictures.* , <code>wp_options</code>.<code>option_value</code> AS 'custom_post_id', GROUP_CONCAT(CONCAT_WS('@@', meta_key, meta_value)) AS 'extras' FROM <code>wp_ngg_pictures</code> LEFT OUTER JOIN <code>wp_options</code> ON <code>wp_options</code>.option_name = CONCAT('wp_ngg_pictures_', wp_ngg_pictures.pid) LEFT OUTER JOIN <code>wp_postmeta</code> ON <code>wp_postmeta</code>.<code>post_id</code> = <code>wp_options</code>.<code>option_value</code>  GROUP BY wp_ngg_pictures.pid LIMIT 1

i’m using
WP 3.8.1 french
ngg 2.0.40
hosting
Mysql 5.0
PHP 5.4.x/PHP5.3.x/PHP 5.2.x
CGI
Serveurs Apache 64 bits
Streaming Audio / Vidéo
Javascript
Liaison SSL 128 bits
Perlmagic via Imagemagick 6.3.9
Zend Optimizer
Perl
Python
WAP Ready

this bad thing appears suddenly after many weeks of using ngg 2.0.40 without any problem.
Any solution ?
Thanks in advance

Olivier

https://ww.wp.xz.cn/plugins/nextgen-gallery/