Why SQL Server Express edition is slower than SQL Server Web edition?

While I was doing a search to identify the differences between SQL Server editions I have found a post in ASP.NET forums that says: "SQL Server Express tends to be slower compared to SQL Server Web edition. This is due to the limitations imposed in SQL Server Express which is basically meant for only development environment. We have observed significant amount of improvements with SQL Server Web edition for production web facing applications on VM's"

Now what limitations开发者_StackOverflow中文版 in SQL Server that make it slower than Web edition? And as one who care about perforamcne will SQL Server express really be a bad choice?

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As seen from the editions matrix, SQL Server express is limited in number of CPUs, memory usage, and total DB size. For small databases, such as with embedded systems, it can be fine, bit it does not scale well for multiuser applications beyond a fairly trivial size.