Mysql, ,базы данных, оптимизация

Доброго времени суток!
У меня проблема со скоростью загрузки сайта. Страницы либо очень долго загружаются, либо выдают такую ошибку: "Error displaying the error page: Application Instantiation Error: Query execution was interrupted SQL=DELETE FROM `r82m0_session` WHERE `time` < '1417506677'"
В тех. поддержке хостинга написали, что это проблема вызвана высокой нагрузкой на базу данных mysql, которая создаётся большим количеством медленных запросов к базе данных.
И посоветовали произвести оптимизацию запросов к базе данных.
Подскажите, как это сделать? Я в базах данных плохо разбираюсь. .

Вот примеры запросов:
2014-12-09 08:29:01: 2.22 (288%) 0/15992 (0%) 10/5168 (0%) 0/3801 (0%) u7999104_bas (in 60 sec)
2014-12-09 08:38:01: 2.75 (70%) 47/10318 (0%) 11/4031 (0%) 15/3631 (0%) u7999104_bas (in 60 sec)
2014-12-09 08:39:01: 2.14 (175%) 0/19650 (0%) 6/7004 (0%) 0/3516 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:18:01: 4.05 (70%) 45/16627 (0%) 7/5662 (0%) 15/2308 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:19:01: 2.86 (285%) 0/14601 (0%) 10/4890 (0%) 0/1717 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:28:01: 3.06 (85%) 31/13555 (0%) 12/5178 (0%) 16/1706 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:29:01: 2.77 (165%) 0/16177 (0%) 6/5043 (0%) 0/1639 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:31:01: 3.03 (73%) 2/21545 (0%) 2/6245 (0%) 4/2051 (0%) u7999104_bas (in 60 sec)
2014-12-09 09:32:01: 2.58 (73%) 1/15561 (0%) 2/4643 (0%) 2/1782 (0%) u7999104_bas (in 60 sec)

WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506513'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506511'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'
WHERE `time` < '1417506677'' by user 'u7999104_bas'