Short answer
WordPress Core Web Vitals improve when the site serves less JavaScript, fewer blocking assets, cleaner templates and faster infrastructure. Caching plugins help, but they rarely solve the root issue on their own.
Start with the bottleneck, not the plugin list
When a WordPress site is slow, the first job is to identify where the page is actually losing time:
- slow server response
- oversized hero media
- third-party scripts
- bloated theme output
- plugin overlap
- database or object cache problems
If you skip diagnosis and install another plugin, you usually add complexity without improving the real metric.
A practical audit order
1. Server response and hosting
Check TTFB first. If the host is struggling, front-end fixes will have limited impact. Look at:
- PHP version
- worker limits
- object cache availability
- CDN behavior
- page cache hit rate
2. Theme and template output
Large DOM trees, unnecessary builders and duplicated assets push up both LCP and INP. Review:
- template bloat
- unused section builders
- large global CSS bundles
- unnecessary sliders or motion libraries
3. Images and video
The hero usually drives LCP. Use:
- properly sized hero images
- next-gen formats where safe
- predictable width and height
- deferred below-the-fold media
4. Third-party scripts
Chat widgets, tracking tools and experimentation scripts often create the biggest INP problem on otherwise decent WordPress sites.
5. Database and autoloaded options
Autoload bloat, stale transients and plugin leftovers can slow the admin and front end. Clean data matters.
What usually moves the metric fastest
In practice, the biggest wins usually come from:
- simplifying the theme layer
- replacing heavy plugins
- improving hero media handling
- fixing cache configuration
- reducing third-party script load
What not to do
Avoid treating score-chasing as the goal. A 95 score that breaks editors or hides conversion tools is not a real win.
The right target is a stable site that:
- loads quickly for users
- keeps editor workflows sane
- preserves measurement and conversion paths
- is maintainable after handoff
A good buyer question
Ask not just "Can you get this site to 90+?" Ask "What is making the site slow, what will be removed or rebuilt, and how will the site be kept fast after launch?"