OK... bit more info for anybody who reads this... I have trapped the IP addresses Premiere is connecting to and the seem to be from cloudfront.net.
This helped me to find this thread:
https://forums.adobe.com/thread/1286200
The first post on this thread contains the 'correct answer' as follows:
"
I tried and found a somewhat devious workaround: Add a dummy entry in my own host file for static.photoshop.com
c:\windows\system32\drivers\etc\hosts
127.0.0.1 static.photoshop.com
PSE now starts without the lag. (my PC rejects my own attempt to get a TCP port 80 session.)
I haven't found yet what that might break that I would be unhappy about.... for now I'm happy with the quick startup.
"
I have tried this and it does in fact stop Premiere from calling out to cloudfront (don't ask me how it works)... I'm testing it now and if there's no issue I'll post again.
GLA,
GRB