I have a slideshow on my home page it takes about 5 seconds to load the first image on a mobile can anyone help with maybe a wait loading ?

So why are you using:

$w.onReady(function(){
}

2 times? You only need to use it once.

Also, are you trying to create a new item?

$w('#dataset1').new();

I could only find that it is to create a new item in the documentation:

Or are you trying to achieve something else with it???
If you are not trying to do that, just remove it. That might be the bug.