One of the goals and constraints of this proposal has been to achieve all the other design goals, whilst also matching or beating the high record set by most.js - which is not just a little bit faster, but an order of magnitude or two faster than alternatives.
Using the benchmark used by existing libraries in this space, Emitter comfortably and consistently outperforms most.js:
$ node ./filter-map-reduce.js
filter -> map -> reduce 1000000 integers
-----------------------------------------------------
Emitter 204.48 op/s ± 2.14% (70 samples)
most (multicast) 21.17 op/s ± 19.64% (37 samples)
most 74.31 op/s ± 22.75% (59 samples)
cb-basics 6.50 op/s ± 17.46% (18 samples)
xstream 4.09 op/s ± 5.73% (24 samples)
rx 5 12.51 op/s ± 6.51% (61 samples)
rx 4 0.67 op/s ± 5.81% (8 samples)
kefir 3.94 op/s ± 24.58% (26 samples)
bacon 0.58 op/s ± 15.76% (7 samples)
highland 1.42 op/s ± 7.54% (12 samples)
lodash 5.82 op/s ± 33.08% (17 samples)
Array 5.88 op/s ± 11.36% (19 samples)
-----------------------------------------------------This is doubly significant because, for performance reasons, most.js does not support multiple consumers by default. In a more equal comparison, if you were to run most.js with multicast support at each node, it would significantly drop it's performance.