Ouch, something got trashed, yes, I'd worry. If it happens again I'd add diagnostic code to see why tcl_url2file("/") fails. The array caching the information got hosed somehow.
You were running in performance mode? actually "/directorynamehere/" sounds suspicious, where does that come from? Which package?
As far as PG vs. Oracle goes ... I haven't noticed drastic differences between the two. Memory usage in PG should mostly be determined by your PG configuration parameters. Speed should be roughly comparable for a wide range of operations.
Make sure you ANALYZEd your tables.
Of course you give two reasons why it might be your fault not PG's fault and I suspect you may be on to something :)
