QTextEdit super slow resize

[bunjee]

QTextEdit * test = new QTextEdit;
QString string;
for (int i = 0; i < 50000; i++)
{
      string += 'o';
}
test->setText(string);
test->show();

QTextEdit * test = new QTextEdit;
QString string;
for (int i = 0; i < 50000; i++)
{
      string += 'o';
}
test->setText(string);
test->show();

To copy to clipboard, switch view to plain text mode 

== Super slow window resize.

How can I optimize this ?