I created a scrollable list with 100 items ( https://i.imgur.com/CuLadCe.png ) and tested if it helps performance to give all list items their own nested canvas but it does not really make any difference:
Without the nested canvases: https://i.imgur.com/4eP0TLN.png
With nested canveses: https://i.imgur.com/M5XhMV4.png
So no real difference, even while scrolling. Does the ScrollRect handle this optimization automatically? Maybe I should test which constantly changing children?
According to this talk from December 2016 it would make sense to add the canvas component to the scroll rect, if I’m not mistaken. Interesting that he didn’t mention canvases being added automatically to the ui.
Unite 2016 - Let’s Talk (Content) Optimization
You should also think about pooling the items if you’re not already doing that. Also take a look at Unity Connect
Ok I just found some information on a blogpost about Unity 5.2 and Optimized Batching :
In Unity 5.2, the batching code was
substantially rewritten, and is
considerably more performant compared
to Unity 4.6, 5.0 and 5.1. Further, on
devices with more than 1 core, the
Unity UI system will move most of the
processing to worker threads. In
general, Unity 5.2 reduces the need
for aggressively splitting a UI into
dozens of Sub-canvases. Many UIs on
mobile devices can now be made
performant with as few as two or three
Canvases.
This might explain why there is no difference on my machine, so maybe using nesting canvases might not be a good idea anymore because it might break more that it adds value/performance?
