Clang model is completely unusable for me

I switched to it in order to have support for std::unique_ptr pointers which is not present in standard one.
However, there are fatal problems that forced me switch back to standard model.
1. Can be too slow. Takes 10 seconds and more. Even after hours of Qt Creator running.
2. Can start crashing. Getting these messages:
"Clang Code Model: Error: The clangbackend process has finished unexpectedly and was restarted."
3. Can not show suggestions at all (at least for local variables).
The project is pretty large.