[REG 3.2.1 -> 3.3.0] Rising CPU consumption

1. Open project tests\manual\cplusplus-tools\cplusplus-tools.pro from Creator's repository in Creator.
2. Configure the project with a kit using Qt 5.3.1, built with MSVC2010.
3. In main.cpp, go to the definition of

   void testCompleteSymbols()
   

4. Keep an eye on Creator's CPU consumption.
   For me, it's at 13% now. Quite high already, considering that Creator is doing nothing at the moment.
5. Uncomment one of the outcommented lines.
   CPU usage rises to 25%.
6. Comment that line out again.
   38%
7. Repeat steps 5 and 6.
   Each time, Creator's CPU consumption rises and doesn't fall.
8. Try to close main.cpp
   Creator freezes completely.

Found while trying QTCREATORBUG-13064. Both issues need the same steps to reproduce them. I can't judge whether they are just two symptoms of the same bug.