Qt Creator gets unresponsive when editing specific strings in a *.pro file

During copy&paste and editing strings of the following format Qt Creator gets unresponsive for several seconds:

DEFINES += APP_A=\\\"test1\\\"
DEFINES += APP_B=\\\"test2\\\"
DEFINES += APP_C=\\\"test3\\\"
DEFINES += APP_D=\\\"https://www.orf.at/news\\\"

Steps to reproduce:

1. Create a new Qt Project.
2. Add the code from above to the *.pro file.
3. Clear the clipboard. Then copy the code from the pro file and insert it somewhere else.
4. Qt Creator hangs.

Scenario 2:

1. Create a new Qt Project.
2. Add the code from above to the *.pro file.
3. Edit the code in the pro file. Qt Creator randomly hangs, especially when editing the "https://www.orf.at/news" part.