There is no direct way to influence the scroll speed of the site. That is directed by the Browser and the OS itself. There are ways to fake it by setting your contents scroll as seen in this jsfiddle.
If you are aiming for a simple paralaxx effect w3schools has a great demo/tutorial.
I think what you are looking for is an effect like this. You can do this with CSS transformations.
.parallax {
height: 500px; /* fallback for older browsers */
height: 100vh;
overflow-x: hidden;
overflow-y: auto;
-webkit-perspective: 300px;
perspective: 300px;
}
.parallax__group {
position: relative;
height: 500px; /* fallback for older browsers */
height: 100vh;
-webkit-transform-style: preserve-3d;
transform-style: preserve-3d;
}
.parallax__layer {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
}
.parallax__group {
-webkit-transition: -webkit-transform 0.5s;
transition: transform 0.5s;
}
.parallax__layer--fore {
-webkit-transform: translateZ(90px) scale(.7);
transform: translateZ(90px) scale(.7);
z-index: 1;
}
.parallax__layer--base {
-webkit-transform: translateZ(0);
transform: translateZ(0);
z-index: 4;
}
.parallax__layer--back {
-webkit-transform: translateZ(-300px) scale(2);
transform: translateZ(-300px) scale(2);
z-index: 3;
}
.parallax__layer--deep {
-webkit-transform: translateZ(-600px) scale(3);
transform: translateZ(-600px) scale(3);
z-index: 2;
<div class="parallax">
<div id="group1" class="parallax__group">
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
</div>
<div id="group2" class="parallax__group">
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
<div class="parallax__layer parallax__layer--back">
<div class="title">Background Layer</div>
</div>
</div>
<div id="group3" class="parallax__group">
<div class="parallax__layer parallax__layer--fore">
<div class="title">Foreground Layer</div>
</div>
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
</div>
<div id="group4" class="parallax__group">
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
<div class="parallax__layer parallax__layer--back">
<div class="title">Background Layer</div>
</div>
<div class="parallax__layer parallax__layer--deep">
<div class="title">Deep Background Layer</div>
</div>
</div>
<div id="group5" class="parallax__group">
<div class="parallax__layer parallax__layer--fore">
<div class="title">Foreground Layer</div>
</div>
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
</div>
<div id="group6" class="parallax__group">
<div class="parallax__layer parallax__layer--back">
<div class="title">Background Layer</div>
</div>
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
</div>
<div id="group7" class="parallax__group">
<div class="parallax__layer parallax__layer--base">
<div class="title">Base Layer</div>
</div>
</div>
</div>