Quite sure that this issue is somwhat related to/in the same realm as the current topic:
The webviews in my extension are quite big in terms of size and rendering etc. React app with alot of contexts, webview messages etc. Possibly performance is somehow what makes this really slow. As mentioned before the views do appear, but that is after something like 2-5 min. Maybe that is some timeout or something.
However i do not see any performance issues in VSCode or Antigravity as mentioned above.