Slowdown since update

The front page of my site which uses the following code seems to have slowed down tremendously. In fact it seems like it doesn’t work at all, although sometimes it eventually loads:

[pass list=A~Z]
[loop exists type="page" parent=this field=alpha value={ITEM} orderby=name]
<strong><span style="font-size: 130%;">{Item}</span></strong>
<p></p>
[the-loop]
[field title-link] ([loop-count type=page parent=this include=children field=type value=resource,dependency])<br/ >
[/the-loop]
<p></p>
[/loop]
[/pass]

I think the slowdown happened after the most recent update (3.6.2), or perhaps the one before (they were both in the last day or two so I might not have loaded that page in between). As there have been significant changes with the parent/child functionality and I use that in this code, I thought perhaps that had something to do with the slow-down.

This is the same code that I needed to upgrade the memory PHP was using in order to get to work. It’s obviously memory-intensive. I’ve added a cache tag to it, but that doesn’t really fix the problem. Any suggestions how I can re-organize the code so it doesn’t have to work as hard?

https://ww.wp.xz.cn/plugins/custom-content-shortcode/