Example template loads very slowly on a cold cache due to excessive image size

On desktop go to https://ampstart.com/templates, clear cache, and open the adventures template. Load time is excessive which appears to be due it loading 29MB of images.

Reproduce the problem at https://ampstart.com/templates by clearing the desktop cache and opening the adventures template. Inspect the template source and its image assets to identify what accounts for the reported 29MB load. Done means the cold-cache load uses substantially less image data and the template opens faster.

Written by the indexing model from the issue text.