Qt Creator hangs for a really long time while reading my project

I am working on my open source project using Qt Creator 3.3 and Qt 5. Whenever I do a "git clean -fxd" in my project directory, then open it in Qt Creator the interface freezes for a very long time while it's "reading project". Some projects take much longer than others, but it seems that it hangs like this for all projects that don't already have a build configuration.

This only happens when I develop in Windows (7). When I do it in Linux everything works fine and the project opens quickly.