Many developers have been encountered issue with slow loading of icons in Android Studio Artic Fox.
The problem is when one tries to search for an icon with Ctrl + Space, the suggestion list keeps loading without return any IconData.
If you keep waiting, the result will be returned but it tooks like 1 minute.
While waiting for an update from Android Studio dev team, you can try one of the following solutions:
Access Terminal in Android Studio and type the following lines:
flutter clean invalidate and restart
Browse Icons in Alternate Source
There are 2 websites which allows user to browse through a list of predefined Material icons:
Both pages show full list of IconData items. I recommend materialui.co because it allows searching by keywords and suggest similar icons if there is no result.
Wait for a fix
If nothing works for you, it is better to file an issue on Android Studio GitHub and wait for a new version.