I am working with lots of parts having their Transparency updated, I would expect turning off CastShadow to disable shadows entirely, but looking at the micro-profiler it would seem this isn’t the case.
(I have included my place file in the private message.)
Expected behavior
Turning CastShadow off should also disable any shadow calculations related to modifying the Transparency, or anything for that matter. I had already assumed this was the case and it seems like a good optimization to make, it just makes sense. If CastShadow is turned back on it can simply cause a shadow update and resume as normal.
I’m no Roblox engineer but this seems totally possible to do, and a worth while optimization to make to help low end hardware.
A private message is associated with this bug report