Branching scenario failing to preview or load Wordpress site

I have created a reasonably complex branching scenario with scoring within my Wordpress site (version 5.3). It was displaying and previewing for the first few levels of branching but now that I have built the whole scenario it won't preview and I can't get it to display from the H5P Content list.

The error message I get in Explorer (version 11.476.18362.0) is 'mywebsite.com is not responding due to a long running script'.

The error message I get in Chrome (78.0.3904.108 (Official Build) (64-bit) is 'Page unresponsive. You can wait for it to become responsive or exit the page.'

The error mesage I get in Firefox (version 70.0.1 (64-bit)) is 'A web page is slowing down your browser. What would you like to do?'

 I then built it on H5P.org and I was saving the whole way but then when I created the whole scenario and tried to preview it, it crashed and I discovered it hadn't been saving all the way. This is what the start of the scenario looks like: https://h5p.org/node/605237

Any help you can give me would be much appreciated :)