Orbeon is slow to load summary pages and perform other operations

Hi,

I'm testing Orbeon 4.4.0.201311042001 on CentOS 6.2 using MySQL 5.1.52 and JBOSS 5.1. Everything seems to work so far, but summary page loads are extremely slow.
Trying to load the Form Runner Home takes around 4 to 5 minutes to just return 30 entries. That is the number we expect, but I don't see why MySQL should use 99% of CPU to return that many rows in 4 or 5 minutes. What am I missing? Is there some performance tuning we should do?
Many thanks!

Actually let me be more specific. The Form Runner Home page is not that bad. But when I try to pull up a form with 400 entries, it takes way too long. Here's the excerpt of the logs:

2014-01-21 09:21:50,772 INFO  ProcessorService  - /fr/service/persistence/search/Safety/Rental_Lease_Activity - Received request
2014-01-21 09:21:50,790 INFO  ProcessorService  - /fr/service/mysql/search/Safety/Rental_Lease_Activity - Received request
2014-01-21 09:21:50,830 INFO  ProcessorService  - /fr/service/persistence/form/Safety/Rental_Lease_Activity - Received request
2014-01-21 09:21:50,845 INFO  ProcessorService  - /fr/service/mysql/form/Safety/Rental_Lease_Activity - Received request
2014-01-21 09:21:50,917 INFO  ProcessorService  - /fr/service/persistence/form/Safety/Rental_Lease_Activity - Timing: 87
2014-01-21 09:21:50,917 INFO  ProcessorService  - /fr/service/mysql/form/Safety/Rental_Lease_Activity - Timing: 72
2014-01-21 09:21:50,921 INFO  DatabaseContext  - Committing JDBC connection for datasource: jdbc/mysql.
2014-01-21 09:21:50,935 INFO  ProcessorService  - /xforms-server - Received request
2014-01-21 09:21:50,953 WARN  XFormsServer  - xxf:instance() - instance not found {instance id: "fr-form-resources"}
2014-01-21 09:21:50,971 WARN  XFormsServer  - xxf:instance() - instance not found {instance id: "fr-form-metadata"}
2014-01-21 09:21:50,971 WARN  XFormsServer  - xxf:instance() - instance not found {instance id: "fr-form-metadata"}
2014-01-21 09:21:51,200 INFO  ProcessorService  - /xforms-server - Timing: 265
2014-01-21 09:23:23,054 INFO  ProcessorService  - /fr/service/persistence/search/Safety/Rental_Lease_Activity - Timing: 92282
2014-01-21 09:23:23,060 INFO  ProcessorService  - /fr/service/mysql/search/Safety/Rental_Lease_Activity - Timing: 92270
2014-01-21 09:23:23,060 INFO  DatabaseContext  - Committing JDBC connection for datasource: jdbc/mysql.

This certainly looks way too slow! We are aware of issues with the MySQL persistence layer, see:

https://github.com/orbeon/orbeon-forms/issues/649

I don't know if what you see is explained by #649, but it might be. In short, the issue is caused by calling XPath from SQL, which is very inefficient.

-Erik