I'm also seeing traffic to AWS just before the IDE "stabilizes"...
Notably a HTTP 301 "Moved Permanently" reply just before the IDE settles down:
1074 15.998826 184.73.237.236 10.100.1.1 HTTP 532 HTTP/1.1 301 Moved Permanently (text/html)
Perhaps something is broken at AWS? The IDE needs to be fixed to remove this dependency!
Why is our IDE contacting the api-builder web site anyway? Someone vacuuming up a lot of code? Grrr?
(Nice workaround hijacking api-builder.arduino.cc!!)