I see no files inside dir ParallaxImage\jquery.scrollspeed in ParallaxImage_1_1b5.zip
But in file ParallaxImage\ParallaxImage.php we have
$page->head_js = $addonRelativeCode . '/jquery.scrollspeed/jQuery.scrollSpeed.js';
Is it an error in adding files or in linking script?
I had a problem with scrolling on b3. After upgrading to b5, it is gone. But I see that the scrolling is smooth only when I use the scroll bar. When I use the mouse wheel or keys, the background image has a lag in scrolling and makes jumps.
The height of the parallax container is almost the entire page. So I see this problem on your demo https://typesetter-addons.grafikrausz.at/Parallax-Image-Fullscale as well.