When you think your mysql is slow , the first step is to analyze your sql query with “Exlain” command.
This is an example
explain select * from table1 inner join table2 on table1.field1=table2.field2 and table.field3 =577458498
It will give you some thing like this , look at the “rows” column , if the number of that column is too high, try to reduce it by changing your query , or add index.
+--------+------+-------------------+---------+---------+-------+------+-----------+ |table | type | possible_keys | key | key_len | ref | rows |Extra | +--------+------+-------------------+---------+---------+-------+------+-----------+ |employee| ref | surname,surname_2 | surname | 41 | const | 1 |where used | +--------+------+-------------------+---------+---------+-------+------+-----------+