Currently the mode transfer overlay has to check whether it should
draw for every single object. For scenes with many instances even
that small amount of work per object can be significant. I observed
the overlay taking 1.8% of the samples in a profile.
This commit removes the mode transfer timer and stores it in a
global map instead. Besides the benefit of removing 8 bytes per
object, the main improvement is that it's now trivial to check
whether the overlay can be completely disabled.
Pull Request: https://projects.blender.org/blender/blender/pulls/140374
c48423256d