[Qt-interest] Poor performance of "setBackground()" API in QTableWidgetItem class in Qt 4.5.1

[Mark Pereira]

Hi Stephen,

I'm using Microsoft Visual Studio 2005 build of Qt4.5.1 on a 32-bit machine.

Regards,
Mark

Stephen Jackson wrote:
> On Thu, Jun 11, 2009 at 4:27 AM, Mark Pereira wrote:
>
>   
>> I have been using Qt 4.3.3 for a while and have recently moved to Qt4.5.1. I
>> have noticed that the performance of the "setBackground()" API of
>> QTableWidgetItem class has slowed down dramatically.
>>
>> I have attached a sample piece of code which can be used to reproduce this
>> problem. In Qt 4.3.3. it takes around 407msec to complete setting the
>> background, while in Qt 4.5.1 it takes 68,567msec for the same task. I ran
>> this test on a Intel Core Duo PC (1.8 GHz) with 2 GB RAM.
>>
>>     
>
> I have run your test and this does not reproduce the problem on my system.
>
> g++ 4.3.2, Ubuntu 8.10 (64 bit)
>
> Running the test 5 times with each of two Qt versions gives the
> following results.
>
> Qt 4.4.3 msec: 297, 256, 225, 317, 221 [Average 263]
> Qt 4.5.1 msec: 434, 279, 270, 340, 402 [Average 345]
>
> Could it be that something else has changed in your environment, other
> than the Qt version? (e.g. debug vs nodebug)
>
> Stephen Jackson
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> Qt-interest at trolltech.com
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>   



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