Does Two-Sided mode for Cast Shadows affect performance?

Hi!

In Mesh Rendered component there is an option for Cast Shadows to be Two-Sided.

Here is some information about it:
“Shadow rendering will turn off backface culling, even if object’s shader has backface culling on. This means that single-sided objects (like a Plane or a Quad) will cast shadows, even if the light is behind them.”

Do you guys know if this mode affects performance too much?

I’m sure you’ve found the answer to your question by now but I’m gonna leave my experience here for anyone who stumbles upon this question.

I ran a few test with a few thousand one sided quads to find the answer to this.
Turns out performance-wise they are the same, “On” vs “Two Sided” have the exact same performance hit.

And it only makes sense, in the shadow projection calculation there’s just the mater of surface normal vs light direction to decide whether or not to include that object, there is actually more instructions involved to check if a surface is one sided (and the dot of its normal with the light direction is greater than zero) to include it in the shadow calculation than just including it without any calculations…

I hope this makes sense.