Large increase in memory usage when using the "\n" character

To test this bug I used Qt example program in /usr/local/Trolltech/Qt-4.5.1/examples/widgets named spinboxes.

This bug occurs on X11 with Qt 4.5.1, 4.5.2, and the 4.6 snapshot.

Just change one of the labels text, just add a \n between the label text. This causes increase in virtual memory of application.
Without \n Virtual memory is 25 MB and with \n in label it is 90 MB.

First run unaltered:

Memory: 3.2 M
Virtual Size: 39.5 M

Second run, with \n character added to one of the lables:

Memory: 8.6 M
Virtual Size: 118.8 M

Third run, after removing the \n character and rebuilding:

Memory: 3.2 M
Virtual Size: 39.5 M