Complex models can cause an unresponsive editor

When loading sketchfab models, I have no idea which will be light and which will be heavy. When I load a heavy model, I can slow down my browser to a crawl. I would like to tell spoke "stop doing work so I can delete this thing"

Start by reproducing the issue in the Spoke editor with a heavy Sketchfab model and trace the model-loading work that makes the browser unresponsive. The change is complete when a user can stop that work and delete the model while the editor remains responsive.

Written by the indexing model from the issue text.