When selecting a large number of records from an SDO_Geometry feature class, slow performance may be encountered in ArcMap.
This can occur if statistics have been built on the SDE_LOGFILE tables.
If using the default shared logfile configuration, each Oracle user making selections in ArcMap will have SDE_LOGFILES and SDE_LOGFILE_DATA tables in their schema. These tables are initially created when each Oracle user selects over 100 records from a feature class in ArcMap. When the logfile tables are first created in the user's schema, they do not have statistics associated with them.
However, if Oracle's default, GATHER_STATS_JOB, is enabled (or the equivalent at Oracle 11g), this job automatically builds statistics for tables without them, including the logfile tables. The logfile tables are very dynamic, so building statistics when there are no records in the SDE_LOGFILE_DATA table subsequently leads to poor query execution when a large selection is made in ArcMap and this table contains thousands of records. This seems to be particularly noticeable with SDO_Geometry feature classes.