Well, I'm not sure that I'm 100% right, but it seems that the “x” value converts every frame for any movement (especially in a difficult parallax situation, where at least 5 layers move in the same way same time) is a very bad idea.
Also, after many studies, SVG1.1 does not support certain CSS3 transformations in all browsers. SVG conversions are fine, but CSS3 isn't.
Finally, to fix this solution: I just reset all x, y positions (0, 0) and positions everything with -webkit-transform: translate3d (x, y, z), (and options for other browsers).
. translate3d 2d z 0. translate3d iPad.