Perf wrapper for Excel VBA

Spoiler

This code is actually BAD for performances! So don't use it! ;)

For a while now, I've been using this wrapper to avoid retyping most of it :

Public Sub PerfWrap(SubNameToRun As String, _
                    Optional ByVal DispStatusBar As Boolean = False, _
                    Optional ArgumentsToPass As String = vbNullString)
    Dim aWB As Workbook, _
        ActiveSH As Worksheet, _
        ScreenUpdateState As Boolean, _
        StatusBarState As Boolean, _
        CalcState As XlCalculation, _
        EventsState As Boolean, _
        DisplayPageBreakState As Boolean
    Set aWB = ActiveWorkbook
    Set ActiveSH = aWB.ActiveSheet
    DoEvents
    With Application
        ScreenUpdateState = .ScreenUpdating
        StatusBarState = .DisplayStatusBar
        CalcState = .Calculation
        EventsState = .EnableEvents
        DoEvents
        .ScreenUpdating = False
        .DisplayStatusBar = DispStatusBar
        .Calculation = xlCalculationManual
        .EnableEvents = False
    End With
    DisplayPageBreakState = ActiveSH.DisplayPageBreaks
    ActiveSH.DisplayPageBreaks = False

    If ArgumentsToPass <> vbNullString Then
        Application.Run SubNameToRun, ArgumentsToPass
    Else
        Application.Run SubNameToRun
    End If

    DoEvents
    ActiveSH.Activate
    ActiveSH.DisplayPageBreaks = DisplayPageBreakState
    With Application
        .ScreenUpdating = ScreenUpdateState
        .DisplayStatusBar = StatusBarState
        .StatusBar = vbNullString
        .Calculation = CalcState
        .EnableEvents = EventsState
    End With
End Sub

I use it like this :

Public Sub Launcher_CopyAndUpdate()
    Call PerfWrap("CopyAndUpdate_Templates", True)
End Sub

Or to pass arguments to the runned procedure :

Public Sub Launcher_Update()
    Call PerfWrap("Update_Templates", True, "Arg1, Arg2")
End Sub

I was wondering if :

• it can be improved regarding performances

• converted as a function to return the value sent b

First, I'd like to echo @Mat'sMug's distaste for your multi-lined Dim statements. There's absolutely no reason to do this at all having them prefixed with Dim makes it completely obvious that I'm looking at a declaration block. It took me a good minute to realize that it wasn't a continuation of Sub declaration, because the Dim literally disappears into a huge wall of code. You aren't saving any time typing it either - last time I checked, Dim and , _ were both 3 characters, and the former is a lot easier to type on a qwerty keyboard.

The other answers hint around the performance, but I'll just come right out and say it. Your Sub should really be named the AntiPerfWrap. First, every single call that Application.Run makes is late bound - even for Excel objects. It has to be, because like CallByName, it is forced to call IDispactch.GetIDsOfNames on itself. This is always slower than an early bound call - period, end of discussion.

You always cache the ActiveWorkbook and ActiveSheet regardless of whether it is necessary or not. I would guess that roughly 1% of all the code I've written requires this. Same thing with .Calculation. Same thing with .EnableEvents. Do I write another PerfWrapWithEvents if I need that turned on? Or maybe PerfWrapWithEventsAllowCalculation? None of this work is free, and it seems like a jumbled collection of "this will make your code go faster anecdotes" collected from SO comments. The cargo cult has found thier messiah in this wrapper.

DoEvents is not free. In fact it's the complete opposite. It yields the processor to every other thread that needs to clear it's event queue. It also makes absolutely no sense to call DoEvents when you've explicitly disabled 95% of the functionality that would make the call useful.

Brass tacks time - let's see how much overhead this wrapper really adds. This is the called routine:

Public Sub UnderTest()
    Dim i As Long
    For i = 1 To 10
        Debug.Print i
    Next
End Sub

And the baseline benchmark:

Public Sub BenchmarkOne()
    Dim starting As Single
    starting = Timer

    Dim i As Long
    For i = 1 To 100
        Sheet1.UnderTest
    Next

    Debug.Print "Unwrapped: " & Timer - starting
End Sub

Unwrapped: 0.8515625

Public Sub BenchmarkTwo()
    Dim starting As Single
    starting = Timer

    Dim i As Long
    For i = 1 To 100
        PerfWrap "Sheet1.UnderTest"
    Next

    Debug.Print "Wrapped: " & Timer - starting
End Sub

Wrapped: 6.492188

Ouch.

Conclusion - Burn it. Burn it with fire. The premise behind the code is that there is a common set of operations that you can do to "speed up" code. In fact, this is never true. In reality, you are turning off Excel functionality that can slow down code. There's a big difference. If you approach performance issues by looking outside of code that you've written, you're starting out looking in the wrong direction. A catch-all "solution" for performance simply doesn't exist, so I wouldn't pretend to be providing it. The best way to look at it is to imagine that any code under performance review to be copied and pasted in place of this...

If ArgumentsToPass <> vbNullString Then
    Application.Run SubNameToRun, ArgumentsToPass
Else
    Application.Run SubNameToRun
End If

...then do a code review on the entire thing. Ask yourself, "In the context of the full Sub, what is the reason for every single line of code other than part above"? I'm guessing that in roughly 99.99% of cases, there won't be a good answer for all of them.

StackExchange Code Review Q#158048, answer score: 10