About performance for Database of millions of records

[yasset perez riverol]

Hi:
I have a database with 30 tables, each table have almost 1 million of records,
perhaps one of them has 300 millions of tuples.
1- I 'm coming from PostGresql database, but with this database when I run some
queries the server was very slow.
2- I read that project as Google used the mysql database as Server of Databases.
Well I assume that this server could be a better choice for my problem.
3- I need, If someone have a document or article with the best practice for
performance, design, implementation of huge databases.?
4- Anyone have some tips that resolve this kind of problem?

Thanks in advance...

Yasset.