C++ – Random Delay When Printing to Dymo LabelWriter Turbo Via ShellExecute()

I have an external program which takes in a few arguments (PrintLabel) which is called from my application using ShellExecute. PrintLabel is shown below. Sometimes it can take upwards to 15 to 20 seconds to print a label. It seems to get worse over time. If the PC is rebooted, then the printing speeds up again but it gets slower over time. Sometimes it is random (i.e. fast then slow). I am using SW_HIDE because I do not want the user to see the console dialog box everytime. I understand it should take a few seconds like a normal printer would, but 15 – 20 seconds seems excessive. Is it a Dymo LabelWriter issue or ShellExecute issue? ShellExecute is called within the UI thread. Any clues?

ShellExecute statement from application:

ShellExecute(Application->Handle, "open", "C:\\Program Files\\Application\\PrintLabel", objdata, "C:\\Program Files\\Application", SW_HIDE);

PrintLabel Code:

…

m_DymoAddIn.Print2(Copies, false, Tray);

…

Here is the CDymoAddIn4.h:

// Machine generated IDispatch wrapper class(es) created with Add Class from Typelib Wizard

// CDymoAddIn4 wrapper class

class CDymoAddIn4 : public COleDispatchDriver
{
public:
    CDymoAddIn4(){} // Calls COleDispatchDriver default constructor
    CDymoAddIn4(LPDISPATCH pDispatch) : COleDispatchDriver(pDispatch) {}
    CDymoAddIn4(const CDymoAddIn4& dispatchSrc) : COleDispatchDriver(dispatchSrc) {}

    // Attributes
public:

    // Operations
public:


    // IDymoAddIn4 methods
public:
    BOOL Open(LPCTSTR FileName)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0x1, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, FileName);
        return result;
    }
    BOOL Save()
    {
        BOOL result;
        InvokeHelper(0x2, DISPATCH_METHOD, VT_BOOL, (void*)&result, NULL);
        return result;
    }
    BOOL SaveAs(LPCTSTR FileName)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0x3, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, FileName);
        return result;
    }
    BOOL Print(long Copies, BOOL bShowDialog)
    {
        BOOL result;
        static BYTE parms[] = VTS_I4 VTS_BOOL ;
        InvokeHelper(0x4, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, Copies, bShowDialog);
        return result;
    }
    void Hide()
    {
        InvokeHelper(0x5, DISPATCH_METHOD, VT_EMPTY, NULL, NULL);
    }
    void Show()
    {
        InvokeHelper(0x6, DISPATCH_METHOD, VT_EMPTY, NULL, NULL);
    }
    void SysTray(BOOL State)
    {
        static BYTE parms[] = VTS_BOOL ;
        InvokeHelper(0x7, DISPATCH_METHOD, VT_EMPTY, NULL, parms, State);
    }
    void Quit()
    {
        InvokeHelper(0x8, DISPATCH_METHOD, VT_EMPTY, NULL, NULL);
    }
    CString get_FileName()
    {
        CString result;
        InvokeHelper(0x9, DISPATCH_PROPERTYGET, VT_BSTR, (void*)&result, NULL);
        return result;
    }
    BOOL SelectPrinter(LPCTSTR Printer)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0xa, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, Printer);
        return result;
    }
    CString GetDymoPrinters()
    {
        CString result;
        InvokeHelper(0xb, DISPATCH_METHOD, VT_BSTR, (void*)&result, NULL);
        return result;
    }
    CString GetMRULabelFiles()
    {
        CString result;
        InvokeHelper(0x12d, DISPATCH_METHOD, VT_BSTR, (void*)&result, NULL);
        return result;
    }
    BOOL Open2(LPCTSTR FileName)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0x12e, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, FileName);
        return result;
    }
    long GetMRULabelFileCount()
    {
        long result;
        InvokeHelper(0x12f, DISPATCH_METHOD, VT_I4, (void*)&result, NULL);
        return result;
    }
    CString GetMRULabelFileName(long Index)
    {
        CString result;
        static BYTE parms[] = VTS_I4 ;
        InvokeHelper(0x130, DISPATCH_METHOD, VT_BSTR, (void*)&result, parms, Index);
        return result;
    }
    BOOL OpenMRULabelFile(long Index)
    {
        BOOL result;
        static BYTE parms[] = VTS_I4 ;
        InvokeHelper(0x131, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, Index);
        return result;
    }
    BOOL OpenMRULabelFileByName(LPCTSTR FileName)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0x132, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, FileName);
        return result;
    }
    BOOL Print2(long Copies, BOOL bShowDlg, long Tray)
    {
        BOOL result;
        static BYTE parms[] = VTS_I4 VTS_BOOL VTS_I4 ;
        InvokeHelper(0x191, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, Copies, bShowDlg, Tray);
        return result;
    }
    long GetCurrentPaperTray()
    {
        long result;
        InvokeHelper(0x192, DISPATCH_METHOD, VT_I4, (void*)&result, NULL);
        return result;
    }
    void StartPrintJob()
    {
        InvokeHelper(0xc9, DISPATCH_METHOD, VT_EMPTY, NULL, NULL);
    }
    void EndPrintJob()
    {
        InvokeHelper(0xca, DISPATCH_METHOD, VT_EMPTY, NULL, NULL);
    }
    BOOL IsTwinTurboPrinter(LPCTSTR PrinterName)
    {
        BOOL result;
        static BYTE parms[] = VTS_BSTR ;
        InvokeHelper(0xcb, DISPATCH_METHOD, VT_BOOL, (void*)&result, parms, PrinterName);
        return result;
    }
    CString GetCurrentPrinterName()
    {
        CString result;
        InvokeHelper(0xce, DISPATCH_METHOD, VT_BSTR, (void*)&result, NULL);
        return result;
    }

    // IDymoAddIn4 properties
public:

};