Children Display macro inside excerpts leads to slow/no page loads

A page with a child display macro inside an excerpt macro should load quickly.

Steps to reproduce:

1. Create a space with Viewport using the HC theme

2. Create page A with Children Display Macro inside the Excerpt macro

3. Create 3 pages as children for page A

4. Open Viewport for the space home page

Expected result:
Page loads quickly

Actual result:
Page takes longer to load or doesn't load at all