Intermittent loading of css, images and external content

Hi,

I’m currently building a site for a close friend and I’m pretty new to wordpress! So forgive any rookie mistakes!

Recently I’m having intermittent issues where sometimes the external CSS for fonts doesn’t load, some images do not load, and I did have an iframe inline that sometimes also failed to load.

I’m not sure why this is happening. It’s like the page drops out when loading sometimes.

NOTES:

1. I recently changed the permalinks to show as ‘pretty’ and had to update a few URL paths to absolute.

2. Is it bad practice to have some files stored in a manually created folder in the root of the site & link to them? (eg. http://mysite/gfx/image.png). Should these be located in the Theme folder in something like ‘content’ or ‘images’?

3. I have mod-deflate compression enabled on the server to try to speed up page loading in case that may be causing a drop out.

4. I’ve modified the template files to include some content that I do not want my friend to be able to edit. (EG some icon buttons that display at the top of the page before the posts begins.) Could inlining custom HTML in the page template files be causing an issue?

5. I’ve been using Hongkiat’s ‘Bare-Responsive’ theme to build on and customise the theme template files.

6. Also installed W3 Total Cache plugin to try to optimise scripts/minify to help with page loading.

7. Google Page Speed flags up Render Blocking Javascript in the header, but I kind of need this to be loaded for several of the elements to be functional. Could this cause a drop out in page loading?

* I suspect it might be down to a few rookie mistakes when amending the template files or possibly changing the permalinks that is somehow causing images and elements to not load intermittently.

I’d appreciate some advice on best practices or clues as to what may be causing the loading issue to occur

Link to the page in question

I hope someone can be kind enough to give a newbie some advice.

Regards

Brendan