Hi Jason,
No problems. Your answers have helped me a lot in finding a solution to the problem.
I suspect there are some problems with the tables as they have been mismanaged for a long time, with no security or control concerns to prevent spammer accounts.
I noticed that all OJS tables (in my database are 170 
) have storage engine like MyISAM instead of InnoDB.
In the tests I did, changing the engine decreased response time from 2 min 32 sec to 34 sec !!!
See the number of table records involved in these SQL statements:
- review_assignments: 6469
- users: 5569
- roles: 7502
- articles: 2879
I’m sure there are a lot of unnecessary records, but removing them without affecting real records is a huge challenge.
Regards,
Renato L. Sousa