I seem to be lucky with SFO security. Since I got Clear and PreCheck, I've never had a very long wait at SFO. I once had a longish wait (maybe 20 minutes) at the D-Concourse. I remember a really backed up situation at International-A once, but my Clear/PreCheck combo got me through that within 10 minutes or so. It might have been 45 minutes for the mere mortals.