React Native Expo building very slowly

Try using Expo in a Simulator on your development machine and determine if it is taking as long as on your device:

• If it is faster than on your test device, then you should check the network connection on your test device
• If it is as slow as on the test device, then you could try to remove node_modules and reinstall them with 'npm install' or 'yarn'. Expo will be redownloaded aswell as all other packages.

In my case, it was a different solution.

I followed the instructions given by jimmylee on the Expo SDK forums, which say:

If you are behind a VPN, try disabling the VPN.

If you are using windows 10, run CMD on your machine and type ipconfig. Take a look at the first Ethernet Adapter. If it doesn’t say Ethernet Adapter Ethernet it means Expo is taking the IP address of something else.

To fix this, go to network connections and disable the adapter that it should not be pointing at.

Connect your computer to the network and your phone to the same network. Restart Expo.

So, go to Settings > Network & Internet.

Click Change Adapter Options:

Then disable the unneeded Ethernet:

Then restart Expo.