Pagespeed is a ranking factor, but it's far from the most important one. I would think deeply about what might make humans engage with your competitor's site for longer than yours.
Thanks for the advice. Will do. But I still fail to understand how this makes SEO a software problem.
SEO also includes: "what meta description can I surface on a SERP that has the highest clickthrough?" so in that sense, it's an A/B testing/software problem.