How many games and files do you have on the external drive ?
Once EmulationStation creates the gamelists for each system, you can turn on the 'Parse Gamelists Only' option and on the next restart it will not re-scan the disc/folders.
@lilbud basically it’ll just continue to boot then next part of the os without waiting for a WiFi signal and will connect when it’s ready in the background . Without it, It’ll wait either for an connection or just timeout and then continue to boot. No need to to have a solid WiFi connection on a retro pie setup. Where you would want it is if your project requires internet or WiFi to run your project so it has WiFi before the whole OS boots.