How slow is it to cold start a Qt Widget application on Windows?

As you know, Qt uses its own widgets rather than using one system provides. So its DLLs are large(at least 20MB or so for just Qt Core + Qt GUI + some default plugins) so that it takes a bit relatively long to cold start the application.

But how long? I took my stopwatch application on my phone and it says it’s about 4 seconds for just showing blank window, but it’s not fair to rely on human sensory as a programmer myself.

So I tweaked the default Qt Widget application provided by Qt Creator as follows:

---

#include “widget.h”
#include <QApplication>
#include <QDateTime>
#include <QMessageBox>

int main(int argc, char *argv[])
{
   QDateTime start=QDateTime::currentDateTime();
   QApplication a(argc, argv);
   Widget w;
   w.show();

   QMessageBox::information(NULL, “Time”, QString::number(start.secsTo(QDateTime::currentDateTime())));
   return 0;
}

---

SImple, huh?

I ran the application on my Pentium which I bought at 2012 or so and found out that it takes 2 seconds to create the widget and show. For warm start(restart), it takes less than 1 second so it’s meaningless.

Anyone interested in this result?