PRB: Compiling to Native Code Can Be Slow

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 5.0

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)

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")

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

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

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

REFERENCES

Books Online, Programmer's Guide, Optimizing Objects

Keywords          : vb5all
Version           : WINDOWS:5.0
Platform          : WINDOWS
Issue type        : kbprb