SphinxCadquery Performance In Docs

First off I like the live previews in the docs, and I'm not suggesting that we pull them back out. However, Firefox complains about the examples page now.

I have tested this on my 1-1/2 year old Linux laptop (Ubuntu 18.04) with a i7 processor and 8 GB of RAM, as well as on a 6 month old Windows laptop (Windows 10) with an i5 and 8 GB of RAM. Same result in Firefox 79.

When opening [this page](https://cadquery.readthedocs.io/en/latest/examples.html) on readthedocs the docs do eventually load, but Firefox thinks there is a script slowing the page down and asks if I want to kill it.


I also had an instance on my Linux laptop the first time I pulled the page up where the first two examples loaded, I started rotating the models, then they locked up while the rest of the page loaded. Since it was my first time on the page, I thought it was stalled.

It seems to be working fine for the community members who have tested it so far, but the message from Firefox is concerning.