What WordPress already does
Since 5.8, WebP uploads work. Since 6.1+, default lazy loading and fetchpriority for LCP images exist. Core creates -150x150, -300x200, etc. from your original. Give core a 1600–2000 px WebP original and the sizes are small by construction.
Why it matters
- Optimisation plugins add cron, API keys and support debt.
- Agencies inherit sites with three overlapping image plugins.
- Client-confidential images never need to hit ShortPixel's servers.
How to do it
- Convert each upload batch locally (or train editors to use the converter first).
- Upload WebP in Add Media. Fill alt text.
- If you already have a messy library, convert the worst 100 files and replace attachments.
Settings that work
Posts: 1200–1600 px / 80–85%. Full-width covers: 1920 px / 78%.
When a plugin is still justified
If 20 authors upload from phones daily and you cannot change behaviour, a server-side optimiser is damage control. For brochure sites and shops with a controlled pipeline, skip it.