When duplicating an action, it is stashed in the NLA on a muted track.
Over time this can slow down blender, because certain code will look at every
FCurve in every action in the NLA.
To fix the performance issue, we can take advantage of the fact that
stashed actions are put onto a muted NLA track.
With this patch any strip on a muted NLA track is ignored in the
Depsgraph evaluation.
Measurements of `DEG_graph_relations_update`
| - | Before | After |
| - | - | - |
| 50 actions | ~140 ms | ~10.0 ms |
| 100 actions | ~250 ms | ~10.7 ms |
Pull Request: https://projects.blender.org/blender/blender/pulls/133864
de31cecfaf