One common performance issue with the MUI library in Meteor is that @mui/icons-material is quite heavy. Importing it eagerly from the index makes the bundles and related processes larger, especially without using specific paths, a Babel import transformation plugin, or modern bundler tree shaking.
In your code I saw a line of code importing eagerly:
Try using import ListAltIcon from "@mui/icons-material/ListAlt instead, and see if the problem persist. Additionally, consider removing dependencies from the project one by one, then re-run it to identify which one is causing the issue.
If the problem continues, we’ll need to investigate it as part of our performance work. I’ve made some notes on this. Thanks for setting up the environment. We’ll follow up once we have more information.