FIX: PSET Method Is Slower in Visual Basic 6.0

A project created in Visual Basic 5.0 uses the PSet method to change the color of pixels in an object. The project is compiled into an executable file using Visual Basic 5.0. When the same project is compiled using Visual Basic 6.0, the executable file runs noticeably slower than the Visual Basic 5.0 version. The expected behavior is that the Visual Basic 6.0 application should run at least as fast as the Visual Basic 5.0 application.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why  (http://support.microsoft.com/kb/194022/EN-US/ )

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed  (http://support.microsoft.com/kb/194295/EN-US/ )

This section demonstrates how to create a sample project that reproduces the bug behavior. It assumes that you have Visual Basic 5.0 and 6.0 installed on the same or identical machines. It also assumes that you are familiar with the PSet Method and compiling projects. If you are not familiar with these tasks, see the REFERENCES section below for more information.

Steps to Reproduce Behavior

1. Start a new Visual Basic 5.0 Standard EXE project. Form1 is created by default.
2. Add a PictureBox, a CommandButton, and a Label control to Form1. Position the Label control so that there is ample room to its right to accommodate 40 characters.
3. Copy the following code to the General Declarations section of Form1:

   Option Explicit
   
   Private Sub Command1_Click()
      Dim dStart As Double
      Dim dEnd As Double
      Dim intX As Integer
      Dim intY As Integer
      
      Picture1.Cls
      dStart = Timer
      For intY = 1 To Picture1.ScaleHeight
         For intX = 1 To Picture1.ScaleWidth
            Picture1.PSet (intX, intY), vbBlue
         Next
      Next
      dEnd = Timer
      Label1.Caption = "Elapsed time: " & dEnd - dStart & " seconds."
   End Sub
   
   Private Sub Form_Load()
      With Picture1
         .ScaleMode = 3
         .TabIndex = 1
         .Top = 120
         .Width = 4215
      End With
      Label1.AutoSize = True
   End Sub
   					

4. Compile the project into an executable file. Run the executable file and click the CommandButton. Note the time shown in the Label control.
5. Open the same project in Visual Basic 6.0. Compile the project into an executable file. Run the Visual Basic 6.0 executable file version and click the Command Button.
   
   BUG: The Visual Basic 6.0 version is slower the Visual Basic 5.0 version.

Please see:

• Topics on Compiling Applications (http://msdn.microsoft.com/en-us/library/aa232747(VS.60).aspx) in the Online Help, or the Microsoft Visual Basic 6.0 Component Tools Guide, or the MSDN Web site at: http://msdn.microsoft.com/en-us/library/aa232747(VS.60).aspx (http://msdn.microsoft.com/en-us/library/aa232747(VS.60).aspx) for more information about compiling your Visual Basic project.
• PSet Method (http://msdn.microsoft.com/en-us/library/aa230482.aspx) in the Online Help, or the Microsoft Visual Basic 6.0 Component Tools Guide, or the MSDN Web site at: http://msdn.microsoft.com/en-us/library/aa230482.aspx (http://msdn.microsoft.com/en-us/library/aa230482.aspx) explains the PSet method.