Allegedly, on or about 17 July 2017, Daniel Miranda sent:
When I press the slash/question-mark (on a PT-BR keyboard) key while focused into a window, or when pressing backspace to erase that slash immediately afterwards, X11 will freeze for about a second consuming 100% CPU. No other key causes the same behavior, not even the slash key from the numeric keypad. I can observe the issue in GTK2, GTK3, Qt and custom applications (such as Chrome and Firefox), but I cannot reproduce the behavior when sending inputs to `xev` for observation. Even GDM is afflicted when typing my user password, before ever having logged in.
Has it been set as the compose key?
e.g. If you type /ae does it turn into: æ
Not that /that/ would explain the 100% CPU pinning, but could explain why the slash is being treated differently from other keys.