How does comp size affect performance?

[rbhun]

Hi
Let's say I have a setup which has 1920x1080 files loaded, and the output size in the advanced panel is 1920x1080, connected to 1080 screens, where is comp size in this equitation?

I can see fps go up if I lower the comp size but is there a downrez happening somewhere?

Thanks
Balazs

[Zoltán]

you see the composition canvas in the output preview, so everything that is outside that and not seen is not rendered.
the final layer textures are this size = composition size,
so I would say the downsize happens when you size your clips to the composition size and the layer texure is rendered.
Layer sizes and controls are basically a duplicate of the clip parameters, so sizing the layer doesn't give you a bigger texture than the composition resolution.

so if you lower composition resolution - you lower the layer texture resolutions which have to be blended and rendered, fewer pixels equals faster performance.