Why SQL takes so long?

I am using Oracle8.0.5 in Solaris (Ultra Sparc I) to support a message
board. Each user has a entry in the USER table, which has 6000 rows.

When one user login, the user login ID and Password is entered and
compared with the record in database. But it take so long , about 5
seconds.

I have created index for login ID and password for it, but still can not
solve the problem.

The system check show that the CPU is 100% for almost 5s, while IO is
almost idle.

Does anyone know what happened?

Ans1:
Perhaps you want to tell us your SQL query and the description and
indexes of your table.

Have you traced the query (sqlplus: set autotrace on)? What are the
results?

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