Yeah but WordPress is an extreme example. Every time a WP blog is posted to HN without a static-page-ifier (caching layer that basically turns the dynamic pages

Yeah but WordPress is an extreme example. Every time a WP blog is posted to HN without a static-page-ifier (caching layer that basically turns the dynamic pages into static ones), it dies within minutes. Normal software doesn't seem to have that problem. I traced it once, and I got to admit there was not an obvious bottleneck (this was 2015 or so). Just millions upon millions of calls into deeper and deeper layers for things like translations or themes. Wrapping mysql_query in a function that caches the result (to avoid doing identical queries) helped a few % I think, but aside from major changes like patching out the entire translation system for single-language sites, I didn't spot an obvious way to fix it. You'd need to spend a lot of time to optimize away the complexity that grew from suiting a million different needs, contributed by thousands of people across many years.