A large part of my work is writing about and sharing the Vuo story. We believe there are all kinds of people who will embrace Vuo once they discover it’s out there. So, my efforts include helping create the Vuo website, writing press releases, submitting conference proposals and generally figuring out how to create excitement and how to spread the word about Vuo. I occasionally help out with Vuo e-mail support and I'm part of the think-tank called "Team Vuo."
We've investigated, and it seems the bottleneck is a Rosetta bug related to how Apple is processing the camera image OpenGL texture. We don't see a fix until we add native ARM support or switch to Metal. In the meantime, you can try changing the webcam to a lower resolution.
The shader is applied once to each pixel in the output image with no multisampling. Make Image with Shadertoy draws a pair of triangles that completely cover the image, with no visible triangle edges. OpenGL multisampling only makes a difference for edges of triangles. Since they aren't visible, OpenGL multisampling wouldn't have any effect for this node, so Vuo disables it to improve performance.