1. Open the project qtcreator.pro from Creator's repository.
2. Wait for all progress bars to finish.
3. Check Creator's memory consumption.
   Here it's stable at 878 MB. (Of course you'll see different values. I just want to give an orientation.)
4. Switch to a different build configuration.
5. Wait for all progress bars to finish.
6. Check Creator's memory consumption.
   Here it's stable at 927 MB.
7. Switch to the previous build configuration.
8. Wait for all progress bars to finish.
9. Check Creator's memory consumption.
   Here it's stable at 941 MB. I don't see why the memory consumption should have grown because there's nothing that has not been parsed before.

When you keep switching from one build configuration to the other, Creator's memory consumption grows by more than 10 MB each time. I suspect that this happens while parsing C++ because that's the active progress bar when the memory consumption rises.

Creator should not consume more and more memory when repeating these simple steps.