The point of not doing it when you type is that if you're actively typing enough and parsing would happen to be slow enough for you to notice (unlikely, but well), it seemed better to keep typing responsive instead of symbol updating -- which you're probably not looking at if you're typing so actively anyway.

So, yeah, `g_source_remove()` is possibly slow, but we never encountered a situation where it was *noticeably* slow, so I didn't bare. Possibly if we're worried, we could create a `GSource` explicitly and attach/detach it at will, not sure.