Perfomance of Qt Gui Application on Windows

[geronimo]

Hi
I developed a gui application on linux. The performance on Linux is very good.
But if I compile the program on Windows Xp(MinGW), the performance is very bad.

It seems, that the filling of a QTableWidget with QWidgetItems is very slow on Windows (about 10 times slower, than on Linux).

Maybe you know, how I can work around the problem. Can I optimize the compiler? Or should I try a different compiler (i.e intel c++, ...)?

thank u

[wysota]

I don't think this is related to the compiler. We're running our software on Windows and we haven't experienced such behaviour. Try profiling your program to see where the slowdown comes from.

[geronimo]

thank u for reply. OK.
But the inserting is definitely slower on windows.

//f.e.:
QTableWidgetItem* item = new QTableWidgetItem();
int num = 54212;
item->setData(Qt::DisplayRole,num);
mytable->setItem(row,column,item);

//f.e.:
QTableWidgetItem* item = new QTableWidgetItem();
int num = 54212;
item->setData(Qt::DisplayRole,num);
mytable->setItem(row,column,item);

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[wysota]

How do you know it is slower?

[geronimo]

Because I tested it on both platforms and that was the result.
But I'll test it once again and post code tomorrow.

[wysota]

But how do you know this particular code is slower?

[geronimo]

I don't know that this particular code is slower.
I guess it. But I'm quite certain that the filling takes more time...

[wysota]

So don't guess, benchmark it.

[ugluk]

I've had a similar problem. The solution was to switch from QTreeWidget to QTreeView, maybe the same applies to QTableWidget.

[Qiieha]

Install the latest MinGW.

[geronimo]

I tested it again:
Fill QTableWidget with 20000 rows(3 columns):
Linux: about 3 sec
Windows: about 5 min

Then I tried it on a different windows machine. I installed the latest QtCreator and QtLibs and compiled the app. Now it was as fast as on Linux.
But I don't know yet, what's the problem on the first machine. But my problem is solved...

[amleto]

have you made sure you ar ecomparing release builds with all iterator checking etc turned off?

[geronimo]

I tested it with the releases and the debugs, the occurrence was everytime the same...