opReports 3.1.10 introduces a newly developed  known_reports_cache  to speed up the loading of reports:

• A new option  'opreports_do_cache_known_reports'  in  /path/to/omk/conf/opCommon.nmis  determines whether this cache is enabled or disabled. The cache is enabled by default.
• Testing on a server with a moderateley large number of generated reports has found load time to view a large report improves from more than 9 minutes to less than 45 seconds with the cache enabled.

When known_reports_cache is enabled and one deletes generated reports manually, on the commandline or in a cron job, it is necessary to update the  known_reports_cache flag files modified time to flag that the cache must refresh - this command will suffice:

• touch /path/to/omk/var/opreports/known_reports_cache/*.flag

Flushing the cache with the above command may also be useful in problem-solving.