I wrote a large VBA program which, in a nutshell, calculates the energy need of buildings. It would be way to much code to post here but firstly it reads a configuration file for each building, then loads some heat load profiles from the disk and then dynamically calculates for 35040 quarter hours which heat producers generates what amount of heat.
On Windows 7 with Windows Defender it just runs smooth and fine, no matter what Excel Version (2007, 2010, 2013, 365 tested).
Now, if I'm running the same code on my computer with Windows 10 and Windows Defender (Excel 365), it is slower by an incredible amount (factor 1000 or so it feels). And strangely, everything is way slower, it is not a certain procedure or event. Loading the files and profiles from the disk takes forever, but calculating the energy needs in the loop (where nothing is transferred from/to the drive) is way slower aswell. The GUI isn't refreshing at all and the whole application just seems frozen.
At the same time MsMpEng.exe is on full load, suggesting Windows Defender has a problem. And surprise, having turned off Windows Defender, everything runs fine.
Now, because there are so many classes/modules/etc. it is hard to say, what may be the problem and I can't upload the code. But at least I have a suspicion. Every class has a Parent Property, implemented as depicted here. The parent property is called very often and all over the code so the extreme slow down would make sense if there was a problem with the CopyMemory-API/Function.
Update 1: I removed the CopyMemory-Function and replaced all the Parents with Circular References. This is no long term solution, but it solved part of the problem. When I wait long enough the calculation starts at some point and is as fast as it's supposed to be. So the problem could be related to API-Functions in general because I use quite a lot for the GUI, namely
Public Declare PtrSafe Function GetDC Lib "user32" (ByVal hWnd As LongPtr) As LongPtr
Public Declare PtrSafe Function GetDeviceCaps Lib "Gdi32" (ByVal hDC As LongPtr, ByVal _
nIndex As Long) As Long
Public Declare PtrSafe Function ReleaseDC Lib "user32" (ByVal hWnd As LongPtr, ByVal _
hDC As LongPtr) As Long
Public Declare PtrSafe Function GetSystemMetrics32 Lib "user32" _
Alias "GetSystemMetrics" (ByVal nIndex As Long) As Long
Public Declare PtrSafe Function SetWindowPos Lib "user32" _
(ByVal hWnd As LongPtr, ByVal hWndInsertAfter As LongPtr, _
ByVal X As Long, ByVal Y As Long, ByVal cx As Long, _
ByVal cy As Long, ByVal wFlags As Long) As Long
Public Declare PtrSafe Function DrawMenuBar Lib "user32" (ByVal hWnd As LongPtr) As Long
Public Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" _
(ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Public Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hWnd As LongPtr, ByVal wMsg As Long, ByVal wParam As LongPtr, lParam As Any) As LongPtr
Public Declare PtrSafe Sub ReleaseCapture Lib "user32" ()
Public Declare PtrSafe Function ExtractIcon Lib "shell32.dll" Alias "ExtractIconA" _
(ByVal hInst As LongPtr, ByVal lpszExeFileName As String, ByVal nIconIndex As Long) As LongPtr
Public Declare PtrSafe Function GetActiveWindow32 Lib "user32" Alias "GetActiveWindow" () As Integer
#If Win64 Then
Public Declare PtrSafe Function GetWindowLongPtr Lib "user32" Alias "GetWindowLongPtrA" _
(ByVal hWnd As LongPtr, ByVal nIndex As Long) As LongPtr
Public Declare PtrSafe Function SetWindowLongPtr Lib "user32" Alias "SetWindowLongPtrA" _
(ByVal hWnd As LongPtr, ByVal nIndex As Long, ByVal dwNewLong As LongPtr) As LongPtr
#Else
Private Declare PtrSafe Function GetWindowLongPtr Lib "user32" Alias "GetWindowLongA" _
(ByVal hWnd As LongPtr, ByVal nIndex As Long) As LongPtr
Private Declare PtrSafe Function SetWindowLongPtr Lib "user32" Alias "SetWindowLongA" _
(ByVal hWnd As LongPtr, ByVal nIndex As Long, ByVal dwNewLong As LongPtr) As LongPtr
#End If
Update 2 (which makes the topic in a way solved):
The reason for the loading-part of the program took so long is because I used the JSON-Converter. And as it turns out there was a similar problem. Since I updated the module and removed every other API-Call everything runs fine and smooth. So it is definitly caused by the API-Calls though I don't know why there aren't that many other people complaining about the huge performance issues. And now I can't tweak the GUI in the way I wan't to and I don't really know how to implement the parent property properly.
