Below SQL query help me to speed up the website and reduce the size of database ( I have maximum 3 GB limit from web hosting account)
TRUNCATE TABLE ps_connections;
TRUNCATE TABLE ps_connections_source;
TRUNCATE TABLE ps_connections_page;
TRUNCATE TABLE ps_guest;
TRUNCATE TABLE ps_log;
TRUNCATE TABLE ps_referrer;
TRUNCATE TABLE ps_referrer_shop;
TRUNCATE TABLE ps_referrer_cache;
TRUNCATE TABLE ps_pagenotfound;
TRUNCATE TABLE ps_mail;
TRUNCATE TABLE ps_statssearch;
TRUNCATE TABLE ps_smarty_cache;
TRUNCATE TABLE ps_smarty_last_flush;
TRUNCATE TABLE ps_smarty_lazy_cache;