The site had a hard rule: no theme file or functions.php edits, and no plugin could be deactivated without sign-off. So every fix had to go through LiteSpeed Cache settings or small WPCode snippets.
The biggest wins were preloading the heading font, lazy-loading a large inline SVG that was pushing content down, fixing a multi-line srcset that LiteSpeed’s WebP replacement was skipping, and taking jQuery out of the defer list because a plugin depended on it loading early. I also added ARIA attributes to an accordion that Lighthouse flagged. Each change was documented with where it was made so the team could reverse it.