Confusing Text #2 (MOSS 2007 - Complete Reference - McGraw Hill)

Here we go again, this is very short, but thought I'd document it:

Book: Microsoft Office Sharepoint Server 2007 The Complete Reference (McGraw Hill)
Page: 22
Focus of text: Excel Web Services
Quote:
"To accomplish this, Excel Services is really two primary components. The first is a
calculation service that handles doing what the Excel client does (calculations, macros, and
so on), but that can also can pull information from programs other than Excel. The other
component is a presentation control that provides Excel Workbook-like functionality such
as inserting and deleting rows, adding data, and so on.
In SharePoint terms, the functionality provided by Excel Services is the same, just housed
differently so SharePoint can apply its own security. The Calculation Service is run on the
Application Server (isolated from Web Services) and provides much better performance."

The Huh?!
Take the last sentence: "provides much better performance". Better than what exactly? Better than Excel itself? I doubt it. Also, if the author meant: better than having it "not isolated from Web Services" than his writing skills need revising.

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