Better late than never, what we ended up doing was changing oai_max_records in config.inc.php to a value of 1. Hardly a convenient solution, but when the server is working correctly the response time is decent. (2.3 s) Even a slightly higher number ended with problematic response times. This change to 1 was enough for OAI-PMH to consider the journal compliant.
We would have liked to try Enrique_Manuel_Touce’s solution, but unfortunately our hosting company did not give us permission to implement that change.
Glad you found a work-around, but I suspect the poor performance of the OAI interface is caused by some underlying database problem like a missing index or some tables using a different MySQL storage than the others (MyISAM vs. InnoDB). I suspect resolving that database problem will allow you to easily turn your oai_max_records back up to the default, and will probably improve performance elsewhere in the system.
Regards,
Alec Smecher
Public Knowledge Project Team