Less cost by setting QWidget's background color?

[cic]

Morning all,

i used QPalette to set the widget's background color. But the cost after that increased a lot.
e.g from 46mb --> 55mb.

One example to see the cost is as followed:

// for testing
   QList<QWidget*> wList;
   for(int i = 0; i < 500; i++) {
      wList << (new QWidget());
   }

// for testing
   QList<QWidget*> wList;
   for(int i = 0; i < 500; i++) {
      wList << (new QWidget());
   }

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And the cost is:
1.png

for(int i = 0; i < 500; i++) {
      wList << (new QWidget());
 
      wList[i]->setAutoFillBackground(true);
      QPalette p(wList[i]->palette());
      p.setColor(QPalette::Background, Qt::red);
      wList[i]->setPalette(p);
   }

for(int i = 0; i < 500; i++) {
      wList << (new QWidget());
      
      wList[i]->setAutoFillBackground(true);
      QPalette p(wList[i]->palette());
      p.setColor(QPalette::Background, Qt::red);
      wList[i]->setPalette(p);
   }

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The cost becomes:
2.png

So is there any way to reduce the cost?