Things that can defer code to a future tick:

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• setTimeout - handled here
• setInterval - handled here
• Promise.prototype.then (It defers, but where's the spec for that?) - can be monkey patched to use rAF
• EventTarget.prototype.addEventListener - Can be monkey patched to schedule event listeners to fire inside an rAF
• await - I don't really think there's anything we can do. When the promise resolves, the next code will run in the next tick possibly outside rAF, and there's nothing we can do about it, or is there? Would monkey patching Promise.prototype.then fix that? Would that only work with polyfills/shims that use regenerator? What about native implementations?

What else?

• generator yield - depends on the controller: asynchronous if the controller does asynchronous things makes the generator continue later in a later tick. The controller can be completely synchronous.

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@gadicc Did I miss anything? You mentioned Meteor implements setImmediate with postMessage? As in window.postMessage? EDIT: Ah, I see, yep.

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Promise.resolve().then appears to be the fastest, which won't be the case if we monkey patch it to use rAF. Some people might want the speed in rare use cases.