Chapter 12: Limitations and Known Bugs

Re-indenting large regions or expressions can be slow.
Add-on fill packages may not work as well as CC Mode's built-in filling routines. I no longer recommend you use filladapt to fill comments.
c-indent-exp has not been fully optimized. It essentially equivalent to hitting TAB (c-indent-command) on every line. Some information is cached from line to line, but such caching invariable causes inaccuracies in analysis in some bizarre situations.