> where's the literature on how those affect user satisfaction? As someone else mentioned, it seems like all the issues you mentioned ultimately create user di

> where's the literature on how those affect user satisfaction? As someone else mentioned, it seems like all the issues you mentioned ultimately create user dissatisfaction because of input delay. In which case FID seems like it'd be a good metric for you to target. I'm not sure about the claim that if you improve FID then all input delay will be reduced for the entire duration of a person's session with your site, but I imagine that FID and general input delay are directly correlated. This is just conjecture however and is not a statement backed by research. Here's a summary of some general research on how users perceive input delay: https://developers.google.com/web/fundamentals/performance/rail#ux https://developers.google.com/web/fundamentals/performance/r... (Tangentially related) The new performance.measureMemory() API may help you correlate memory leaks with business metrics: https://web.dev/monitor-total-page-memory-usage/ https://web.dev/monitor-total-page-memory-usage/