Q176435: PRB: Compiling to Native Code Can Be Slow

Article: Q176435
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbVBp500 kbVBp600 kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

When compiling a large project to native code, especially with optimizations
selected, the compile time may be so long as to give the appearance of having
"hung" the machine. Because there is no status bar to indicate the progress of
the compiler, the only indicator available is to watch for hard drive activity,
which may only occur once or twice a minute as this is a CPU intensive activity.

CAUSE
=====

This is by design. Compiling to native code takes more time than compiling to
p-code. There are some techniques suggested below for taking advantage of some
Visual Basic language features to speed up compile time.

MORE INFORMATION
================

Using the techniques outlined below can result in significantly faster compile
time. In some cases it has reduced compile time for large projects from over an
hour to less than 10 minutes.

Minimize the Dots
-----------------

When referencing objects in Visual Basic, you use the dot syntax '.' to navigate
an object's hierarchy of collections, objects, properties, and methods. It is
not uncommon to create very lengthy navigation strings. For example:

     ' Refers to cell A1 on Sheet1 in the first workbook
     ' of an Microsoft Excel spreadsheet.
     Application.Workbooks.Item(1).Worksheets.Item_
     ("Sheet1").Cells.Item(1,1)

In addition to being a rather lengthy string to type, this line of code is fairly
difficult to read and it is extremely inefficient.

The compiler must resolve each dot every time a dot is encountered. To write
applications that compile quickly, minimize the use of dots when referencing an
object.

You can usually minimize the dots by analyzing the objects and methods available
to you. For example, the above line of code can be shortened by removing the
Item method (this is the default method for collections anyway, so you'll rarely
use it in code) and by using the more efficient Range method:

     ' Refers to cell A1 on Sheet1 in the first workbook
     ' of an Microsoft Excel spreadsheet.
     Application.Workbooks(1).Worksheets("Sheet1").Range("A1")

You can shorten this even further by rewriting the code so that it refers to the
active sheet in the active workbook, instead of a specific sheet in a specific
workbook:

     ' Refers to cell A1 on the active sheet in the
     ' active workbook.
     Range("A1")

Of course, the above example assumes it's OK to refer to cell A1 of any sheet
that happens to be active.

Use Set and With...End With
---------------------------

Using the Set statement also allows you to shorten navigation strings and gives
you a bit more control over your code. The following example uses the Dim and
Set statements to create variables that refer to frequently-used objects:

     Dim xlRange As Object
     Set xlRange = Application.ActiveSheet.Cells(1,1)
     xlRange.Font.Bold = True
     xlRange.Width = 40

Visual Basic provides the With...End With construct to set an implied object
within code:

     With Application.ActiveSheet.Cells(1,1)
        .Font.Bold = True
        .Width = 40
     End With

REFERENCES
==========

Books Online, Programmer's Guide, Optimizing Objects

Additional query words:

======================================================================
Keywords          : kbVBp500 kbVBp600 kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Issue type        : kbprb

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