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after I launched Safari, while it was idle and not at any web page ... it was contacting Google, doubleclick, and edgesuite (no idea what this is).
What do you have as a "home page?" I suspect it is
not a local file but some web 'portal' somewhere. If so, it undoubtedly will have ads from at least one company, even if it's just the place that serves the page. In FF, one could use AdBlock and such to prevent seeing those adds and I thought, letting their server run a script to record your use. Safari is much less 'programmable' in things like that, although there are several apps you can add, now.
Back to the activity while it's "doing nothing." That's exactly what LS is there for. While the user will usually see no activity on the screen, many javascripts are busy collecting and reporting what's happening, what page you're viewing, how long it's been viewed (even if you are asleep!), etc. It's always been happening, you just won't know it if LS or something like it is installed (or you like using Terminal!).