Invoke component

I'm writing some integration between Rules and CTools, and have more than once ended up in the situation that I need/want to invoke a component (say, rule set) and can't know how many parameters there will be.

For events there is the handy rules_invoke_event_by_args (as compared to rules_invoke_event), but I can't find anything like this for general components.

So far I have resorted to call_user_func_array, which I suspect is quite slow. Does anyone know a better solution for this?