You can reduce the amount of logging by editing the WEB-INF/classes/log4J.xml file. At the bottom of the file you should find this:
<root> <level value="info"/> <appender-ref ref="async"/> <appender-ref ref="stdout"/> </root>Change "info" to "warn" or "error", depending on what you want in your logs. You can also edit the category tags. See the log4j documentation for more information about the file.
Not sure what the issue with the OPC data source is (i didn't write it). But, out of memory exceptions usually mean that you should allocate more memory to your instance.