I built a simple layout with some examples of nested surfaces. If I run it on my PC I get 60 fps with case 1 (just a single surface), 30 fps with case 2 (two nested surfaces) and about 15 to 20 fps with case 3 (three nested surfaces). You can change the level of "nestyness" in the layout option, I'd like to know how it performs on other machines.
In the past I used some tricks to speed up scrolling in this situations (adding and updating a text item for example) but now I really want to know what is happening and how to speed things up.
Hope someone can help!