Binaryworld - The MapPath method slows down execution ... [ ASP -> General Programming ]

The Server.MapPath method slightly shows down the execution of your ASP scripts, because IIS has to access some internal variables. For this reason you should try to avoid it if possible. In other words, you should code absolute physical paths in your ASP code, instead of using virtual paths that you then have to convert to a physical path using Server.MapPath.

For example, instead of the following code:

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Dim fso, ts
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set ts = fso.OpenTextStream( Server.MapPath("/textfile.txt") )
...

you should use:
Dim fso, ts
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set ts = fso.OpenTextStream( "c:\InetPub\wwwroot\textfile.txt" )
...

The problem, of course, is that using physical paths makes it difficult to move your site to another machine, such as when you move your local web site to the production server. A simple workaround, that avoids the overhead of using MapPath but keeps most of its flexibility, is to store the application's root path into an Application variable, and then use it to build absolute paths. For example, you might set this variable in Global.asa:

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' in the global.asa file

Sub Application_OnStart()
Application("RootDir") = "C:\InetPub\YourSiteDir"
End Sub

and use it elsewhere:

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' in any other ASP file
Dim fso, ts
Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set ts = fso.OpenTextStream( Application("RootDir") & "\textfile.txt" )

Using this approach, you'll have to modify only global.asa when moving to another physical location. Even better, you can retrieve the site's root directory dynamically, so that you don't even have to modify global.asa:

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SUB Application_OnStart
' store the application's root path, whatever it is
Application("RootDir") = Server.MapPath("/")
END SUB