A typical rescue starts the same way: forty-plus plugins, three page builders' worth of leftover shortcodes, and a homepage that takes most of a coffee to appear.
Audit before you delete
Clone to staging, then record which plugin is responsible for which front-end feature and which database tables it owns. Deleting a plugin that quietly powers a form is a bad afternoon.
Group findings into keep, replace, and remove. Most sites can retire between a third and a half of their plugins without losing a single feature.
Cut the request waterfall
Dequeue plugin CSS and JS on pages that do not use them, consolidate icon fonts, and remove duplicate jQuery loads left behind by old themes.
Move the slider or animation library off the critical path, or replace it with CSS where the effect is decorative.
Cache, compress, and verify
Add page caching, object caching where the host supports it, modern image formats, and a CDN. Then re-test on a throttled mobile connection, not on the office fibre.
Finish with a rollback plan and a documented plugin list so the site does not drift back within six months.