It appears that as part of its security routines Apple does do a lot of phoning home. Not to send data but to download things like the latest XProtect signatures database, verify application checksums and signatures to b4r duty sped str legitimate and unmodified, verify subscriptions are current, establish iCloud links and be sure try have the latest data, etc. Because you had/have a WiFi network connection those various tasks each attempt to connect to the internet and eventually time out if a connection cannot be established. Thus making start up and application launch feel glacial.
Thanks. That sounds absolutely logical to me, so I'm going with that explanation....and good to know for future reference. Or, if someone else has the problem and asks me, I get to look clever.
As to the switching between versions, I suspect you may have been re-booting. I have long held the opinion that reboots are not the same as cold boots (shutting down, pause ten seconds, then boot) and can lead to variable, sometimes often undesirable results, so I vastly prefer cold booting. (Installer boots, re-boots are an exception.)
Actually, I did both. The cold starts had time between 'shut off/turn on' as I thought an SMC reset might help.
