Why is enumerating installed MSI packages so slow ?

Question

This is a follow up from this question.

I'm using this slightly modified script to enumerate all installed MSI packages:

strComputer = "."

Set objWMIService = GetObject("winmgmts:" & _
    "{impersonationLevel=impersonate}!\\" & _
    strComputer & _
    "\root\cimv2")

Set colSoftware = objWMIService.ExecQuery _
    ("SELECT * FROM Win32_Product")   

If colSoftware.Count > 0 Then
    For Each objSoftware in colSoftware
        WScript.Echo objSoftware.Caption & vbtab & _
        objSoftware.Version
    Next
Else
    WScript.Echo "Cannot retrieve software from this computer."
End If

What is surprising however, is its abysmal performance. Enumerating the 34 installed MSI packages on my XP box takes between 3 and 5 minutes !

By comparison, the Linux box that sits besides is taking 7s to enumerate 1400+ RPMs... sigh

Any clues on this ?

Answer 1

I suspected a network issue and Wireshark proved me right.

It seems that Windows Installer happily attempts to reopen all the original .msi files, including those who lived on network shares...

Does anybody know a way to disable this behavior ?

Answer 2

When you are using the api functions which are declared in msi.h you are at light speed. i'm using the api for my software software-uptodate and enumerating hundreds of packets takes a second at all.

Answer 3

Extreme slowness is a known/common problem for enumerating Win32_Products

If you need an alternate solution, consider building your own list of products using the 'Uninstall' registry entries (as suggested in one of the answers to the original question you referred to).

Some general references for enumerating Uninstall:

• TechNet VBScript example: List Installed Software
• Microsoft KB: How to enumerate the software products that can be uninstalled on a computer

And to do it remotely, use the WMI registry class, StdRegProv. TechNet even conveniently provides a simple example of using StdRegProv to do the very thing you want: How do I list all the installed applications on a given machine