A lot of customers have been asking me if they need to use Enterprise Edition. the basic answer is that EE is sold mainly on the enhanced features which can be compared at:
You will need to look at EE for sure if you require:
But what if you do not require any of the advanced features because you are using a shrink wrapped database for use with a product like MOSS, or just the DbEngine for a relation engine. Does Enterprise offer any performance benefits? the answer is YES.
There are some key enterprise edition only performance benefits across RAM, Parallelism, Query Plans and DISK I/O that will lead to better performance on high end systems, which I will try to list here.
1) Lock Pages in Memory
Lock Pages In Memory" allows SQL Server 2005 to manage its own memory (as opposed to having the operating system do it). It is extremely important to give this right to the SQL Server Service account, especially on 64-bit SQL Server 2005 systems with lots of RAM. It also is required on 32-bit systems to enable AWE.
2) Advanced Scanning (aka Merry-go-round scan)
In SQL Server Enterprise Edition, the advanced scan feature allows multiple tasks to share full table scans. If the execution plan of a Transact-SQL statement requires a scan of the data pages in a table and the Database Engine detects that the table is already being scanned for another execution plan, the Database Engine joins the second scan to the first, at the current location of the second scan. The Database Engine reads each page one time and passes the rows from each page to both execution plans. This continues until the end of the table is reached.
See http://msdn2.microsoft.com/en-us/library/ms191475.aspx and Merry-Go-Round Culprits for performance variances
3) Larger Read Ahead Buffering on Storage Devices
Determining I/O section mentions that EE does up to 1024k read ahead buffering on a Storage Area Network (std only does 64k). This indicates that EE is more suitable to SAN’s which need more buffering due to increased latency.
4) Large Page Extensions
SQL Enterprise Edition retrieves pages up to eight at a go.
5) Parallel index Operations
This is particularly useful in data warehouses where indexes may be frequently dropped and re-created.