GetRelevantAnimLength() and FastPath optimization

I want to have multi-threading enabled in my Anim Blueprint. So i’m trying to ensure that all the nodes in the AnimGraph are on the fastpath and that lightning bolt displayed on them. But I need to use “Get Relevant Anim Length” in one of my transitions between states, but it seems to be incompatible with FastPath.

If I connect this graph the lighting bolt goes away. I’d like to know if I leave the FastPath on this one transition does that mean my whole anim blueprint will not longer be multithreaded?

Can I get around this by adding a Native Transition Binding instead? I’ve successfully added a native binding and it works. But I am unsure if this anim blueprint still gets a multi-threaded update. Can anyone shed some light on this?