Does UE4 use Vsync Prediction for VR?

Development Rendering
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Hello everybody(, especially UE4 graphics devs)!

Does UE4 make use of some kind of Vsync prediction to delay rendering of a frame to keep latency low for VR?
If so, would it be possible that a sudden increase in rendertime (due to particle spawning for example) can cause frame misses even with 4-8ms frame render times?

Assuming yes: Is there a way to tell the underlying system that an increase in rendertime is incoming?

Thank you in advance!
Cheers,

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I would still be interested in an answer, if any Epic Devs come across this :wink:

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For anybody coming accross this, I found this blog post: The Vanishing of Milliseconds. Optimizing the UE4 renderer for Ethan… | by Leszek Godlewski | Medium (Highly recommend it, well written and very interesting for anybody interested in VR performance.)

While describing r.FinishCurrentFrame, the article states that this is no longer recommended and instead mutliple frames should be queued ahead of time, which can improve performance.

I see this as a hint that no vsync prediction is used, and I have not seen anything like that in the code up till now. Cannot guarantee it, though.