I had an issue with
yarn start last week, and there should have been an update to it.
For me, it had the very same bottleneck.
I tested the same code from a Macbook machine and it worked flawlessly.
From my machine (Ubuntu 20.04 LTS) I tested other react projects and the
npm functions on those, and they worked well.
The only issue seems to be that
yarn start and
yarn dapp don’t work with dappstarter on my ubuntu machine.