MySQL database performance issue. (MyISAM)

Im having online online auction website running live since near about 3 years and still going good. Within 3 years so many auctions has been listed on server and completed too. but now there are a lot of load on server as there are so many completed and live auction on database server. Therefore performance of website is not what it was earlier. What should I do to improve the performance ? All table are created using storage engine "MyISAM".

Solution

Read this frist

Basic & the frist thing you can do is index the tables.
You will have to switch MyISAM to InnoDB. Read More
You can Backup the existing data and start from the beginning if possible

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