QTextEdit (QTextBrowser) large memory consuming

Here is the case to represent this strange behavior:

• take a large txt file (plain text, ~2-3Mb). We use "War and Peace" book txt version, with ~47K blocks inside (every line is a text block).
• open it somewhere to copy and then paste to QTextEdit.
• the size of app is expanded from 4Mb to 50Mb, it's ok.
• finally click "Eat memory" button, which is connected to the test slot.
• we have about 250Mb app now, too much, isn't it?
  The example slot does nothing, we have much more complicated logic, but we use these looking-through-blocks loops.
  We have attached test project and war_and_peace.txt file, so you can easily check out this issue.