SQL2005 Enterprise Database Engine Performance Features (versus Standard)

Can anyone comment on the engine performance difference between SQL2005 Enterprise Edition versus Standard? I'm talking generalized performance of the engine and not admin features (parallel index operations) or scaled-storage (partitioning)

( http://www.microsoft.com/sql/editions/enterprise/comparison.mspx )

The marketing literature makes note of two things:

Enterprise can use more then 4 processors

Enhanced read-ahead and scan (super scan)
(note: I cannot find anything about this 'feature')
One un-noted Feature:

only Enterprise supports 'lock pages in memory'


We are in the process of migrating from SQL2000 to SQL2005 in an OLTP environment. Based on the marketing literature; I would have chosen SQL2005-standard. But based on our limited testing, we are seeing some strange differences.

Query Performance

With MaxDOP=1 and using a large batch query (select top 1500000); SQL2005-Enterprise is twice as fast as SQL2005-Standard.

(Note: this difference persists regardless of lock-pages-in-memory setting)

CPU Utilization

In addition, taskmgr shows that SQL2005-Enterprise uses a single processor at ~90%. While SQL2005-Standard shows a single processor at ~20%.

Lock Behavior

We are also seeing lock-behavior differences. A single DML statement that attempts to modify ~5000 rows will cause Table-locks on SQL2005-Standard but obtain normal row-locks on SQL2005-Enterprise.



These empirical differences make me wonder if the engine codebase is fundamentally different between the two?

Any insight would be appreciated.