Yes, or emplace.

receiversRegistry_.emplace(eventID, &receiver);

Yeah, your version benches the whole process indeed. Though your question raised a more pragmatic interrogation to myself, since I think that your bench isn’t a real use case. In a typical scenario, you would initialise the receivers only once and you won’t fire all the events at the same time. So I went for the “tight loop” bench, and it was also my first occasion to use quick-bench.com too 😀

But your benchmark is of vector vs multimap, and of course vector wins. I wanted multimap vs map of vectors. Something like this:
http://quick-bench.com/15HxVdRoWS_bAiIawmf92UMpGVE

Still, the map of vectors wins.

you may also use initialisation list for the subscribe.

receiversRegistry_.insert({eventID, &receiver});

I tried this bench : http://quick-bench.com/1VOnVezx3H4vAG22PPPPmt-29Hk

It may not be very representative (and may be erroneous), but the result goes in your (and expected) direction.

I benched an emit use case (without the search for the key).

It is worth mentioning that in this specific use case (events), you won’t have so many events to notice the difference IMHO.

if (receiversEntry != end(receiversRegistry_))
{ … }
Becomes:
if (receiversEntry == end(receiversRegistry_)) return;

Good point, it makes the code more concise by using C++14 auto in lambda. I’ve included your remark into the article, thanks Romain.