I think this is related: https://forums.opera.com/topic/17154/slow-scrolling-for-modal-windows
Posts made by winblood
RE: Slow scrolling for modal windowsOpera for Windows
Not at all. It looks like all issues are solved in Opera Developer (v41) except in the Speed Dial and scrolling in modal windows. If I activate opera://flags/#enable-gpu-rasterization in Opera Dev, then it's silky smooth, but there is rendering actifacts.
Slow scrolling for modal windowsOpera for Windows
This affects Opera 40, Opera 39 was fine. When scrolling HTML modal windows, the scrolling is jerky and uses alot of CPU with < 20 FPS. This performance issue is also present in several settings pages:
Bookmarks (seems better),
Pages not affected:
I would say that the rendering method was changed?