When scrolling via the mousewheel on https://www.tagesschau.de/ in e.g. simplebrowser, the scrolling is very laggy (there's e.g. a noticable delay before scrolling starts, compared to Chromium).

This seems to be because of the background image CSS rule:

body.tagesschau {
    background: #015999 url(../img/tagesschau/background/base.jpg) repeat-x fixed top;
}
body.tagesschau {
    background: #08335e url(../img/tagesschau/background/base.jpg) repeat-x fixed top;
}

If that rule is disabled in the inspector, scrolling is smooth again.