nickyliu We have been told that this bug had been fixed in Maya 2019.
We haven't extensively tested the fix on our end yet. We'd be keen to hear results of your testing though, if you manage to do any.
If you still observe a big slow down when running substeps with full-frame playback, this work-around is then likely still required.
For clarity, we only observed this performance impact in situations where a deformer likely requires worldSpace vertex position lookups in a time context that is different to the current one ( Maya's own wrap is an example of one such deformer ).
When we first observed this in Maya 2018, we rewrote all of our nodes to avoid this issue, but we are unable to avoid this issue if introduced by nodes written by others if the underlying Maya issue still exists.
I'll do some testing myself and report back to this thread.
-jj