This optimizes a few loops that become significant bottlenecks during
viewport rendering of scenes with large numbers of curves.
To render a curves object, Blender needs to generate a potentially
very large (but trivial) index buffer. As previously implemented,
this index buffer is generated in an extremely inefficient manner,
with a single-threaded loop and an explicit function call per entry.
The buffer then needs to be pushed onto the GPU, which is also a fairly
slow task.
The PR generates the index buffer directly on the GPU with compute
shader.
Pull Request: https://projects.blender.org/blender/blender/pulls/116617
7f43699ebf