Previously, we only measured the execution time of built-in nodes. To get
execution times of node groups, the time of each nested node was accumulated.
This can lead to very bad accuracy when multiple nodes are evaluated at the same
time.
With this patch, we measure the time spend in each compute context more directly
instead of relying on accumulating many small measurements. This also opens up
some potential optimization opportunities, because we can skip measuring the
time for contexts that we don't care about. However, that is not implemented
yet.
The time shown in the UI can still be misleading when many things are going on
at the same time, but it should at least be more accurate in more situations
now.
Pull Request: https://projects.blender.org/blender/blender/pulls/127658
8af75d2fcc