"Format instead of indenting" option is not respected, adding newline takes 16 seconds

When I press enter in a large source file, it takes 16 seconds for the new line to be inserted. During those 16 seconds, Creator completely freezes and top shows 100% CPU usage on the qtcreator process.

If I disable the "Format instead of indenting" option, one would assume the problem would go away. But actually, nothing changes. Inserting a new line still takes 16 seconds with a complete freeze.

The only way to fix this is disabling the clang-format plugin. However, this should not be necessary, as disabling the aforementioned option should already prevent Creator from using clang-format, but it looks like it doesn't. And of course disabling that plugin means that I can't format the code manually anymore either.

A source file where this happens:

https://raw.githubusercontent.com/libretro/RetroArch/master/retroarch.c

No project needed, just open and try to edit this file without a project.