Validation of Partitioned table Performance
Why would you expect performance to be different with partitioning? Partitioning improves manageability but performance depends greatly on the workload and queries.  For example, if you have a useful index on the DateColumn, you will likely get the same performance with and without partitioning.  With no index on the column, performance may be better with partitioning as long as only the needed partitions are scanned due to elimination.  But if an index can prevent the scan, that would provide the greatest performance benefit.