Performance in subconsult

Hello there!

I have the next query:

psql# select * from table1 t1 where not exists (select * from table2 t2
where t2.id = t1.id);

The execution of this uses more than 90% of my CPU performance and the
answer is slow...

Is there any wrong on my query?

Thanks for the posible answers.

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Sonia Sanchez Diaz
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