Qt WebEngine page print preview uses extreme amount of RAM

Using 1.2 GB to preview an 11 KiB file is excessive.

Steps to reproduce:

1. Generate an HTML file using the attached script:

   ./generate_html.sh test.html 1000
   

2. Load the generated file in place of data/index.html in the WebEngine Widgets PrintMe Example.
3. Start monitoring RAM used by the printme process in a system monitor.
4. Press Ctrl+P.

Actual results: RAM usage grows from less than 100 MiB to 1.3 GiB after the 4th step - both in Qt 5 and Qt 6 versions, in Debug and Release modes. A two times large file (pass 2000 to generate_html.sh) makes printme use 2.5 GiB of RAM.

Expected results: several MiB, not GiB should be used by such a preview.

Note: using a high-resolution printer for the preview in the printme example exacerbates the problem greatly: 2.1 GiB of RAM for a 100-number (10 times smaller) file.