Vimeo video embed quality & preload

Hey folks,

I’m having trouble with the quality/resolution of videos I embedded via vimeo.

On our home page we are using two tab panes, each promoting a different solution of our product.

Within those tabs, on desktop we again use another layer of tabs (on mobile we use sliders) and each of these contains the product explanations along with the video content. The videos are embedded (iframes) and hosted on vimeo. They are all set to autoplay, loop, etc. and it works fine.
However, the quality/resolution of the videos that are not in the pre-selected tab pane is bad. Therefore I tried the ‘quality=720p’ tag within the video embeds but somehow it’s not working.

Here’s an example of the html embed code I used for all of the videos:

<!-- embed responsive vimeo video muted and autoplay -->
<div style="padding:56.25% 0 0 0;position:relative;">
  <iframe src="" style="position:absolute;top:0;left:0;width:100%;height:100%;" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>

Any ideas, what I’m missing or how I can fix this?

Really appreciate your help & advices.
Cheers, Jannik

Here is my site Read-Only:

Refer to the Vimeo API for guidance. If documented features are not working with it then I suggestion you reach out to Vimeo.