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By default, OSL executes shaders in a "vertical" fashion, instead of across a grid of points like other PxrPattern nodes. This can result in a loss of efficiency if many textures are accessed and the setup for the textures is executed continuously across an group of shading points.

However, there is the option default to use "Batched" mode. This mode will run multiple shading points via hardware supported vectorized instructions. Speedup with batched OSL is workload dependent -- scenes with a high amount of ray divergence and thus less shader coherence will see less improvement.  Scenes with high coherence such as single-bounce or PxrVisualizer and OSL shaders of a significant size will see more improvements. We take care to perform the optimization only when necessary to provide the best performance overall.

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