When departing Zurich International, how early do you check in? Their app indicated only 90 minutes, which seemed optimistic but I've never flown out of Zurich.
ZRH is not that big an airport, BUT, if it is on a Saturday during ski season, which is "punter turnover day", it can be a madhouse. Give yourself at least 2 hours. Also, if flying back to the US, you might get randomly selected for an extra special security check at the gate which is a pain and takes about 10 minutes. I think that tends to happen to people who show up at the gate early. Keeps the TSA happy if they see they are making efforts to keep us all safe. The guy going through all my carry on stuff was kind of rolling his eyes like "This is such a godawful waste of your time and mine."
I've flown through ZRH many, many times at all times of the year. Like all things Swiss, its insanely efficient. Your worst part will undoubtedly be checkin since many of the counters are shared. If you go through at a busy time, ie Monday mornings or Thursday afternoons, it can be a little crazy, but 2 hours is more than enough. 90 is enough if you're on an intra European flight.
Incidentally, the Swiss version of TSA profiles. So don't be alarmed if someone talks to you randomly in line and asks about your travels while in line. A few years after 9/11 I was checking in with my father and aunt present with me (but not flying). My dad joked about security in Swiss German, and I replied in English and later in Swiss German to my aunt. Somehow that set off an alarm and I was pulled out of line, brought to a room in the bowels of the airport and given a very thorough questioning. What happened to me undoubtedly won't happen to you, but if any questions are asked of you, answer honestly, don't get defensive and you'll have nothing to worry about.