Define the image problem before selecting a plugin. An oversized source, missing responsive variants and late-loading hero image require different fixes.
Start with core and the source image
WordPress can generate attachment sizes and responsive image attributes. It does not mean every uploaded photograph has an appropriate composition or efficient file size for your layout. Crop and resize sensibly before uploading when practical.
Inspect a public page's image requests. Identify which files dominate transfer and which image becomes Largest Contentful Paint. Follow the responsive-image guide before assuming a format-conversion plugin will solve the problem.
Compare the operations separately
| Operation | Question to ask |
|---|---|
| Compression | Is it lossless or lossy, and can the original be recovered? |
| Resizing | Which maximum dimensions are used and which variants remain? |
| Conversion | Which formats are generated, and does the server support them? |
| Delivery | Do browsers actually receive the appropriate variant? |
| Remote processing | Where are images sent and stored? |
| Bulk work | What happens if the job exceeds host resources? |
Lossy compression can change appearance. Format conversion can create additional files without reducing what the browser downloads if delivery is not configured. Keep those distinctions visible during selection.
One documented option: EWWW Image Optimizer
EWWW Image Optimizer documents image optimization and WebP options. Its listing describes local processing with server tools, requiring compatible hosting capabilities, as well as remote API and paid service options. Ask your host whether the required local operations are available.
Paid Easy IO/CDN features and the base plugin have different capabilities. The current listing describes CDN-based resizing and format delivery, including AVIF, separately. Check the exact package for your intended workflow rather than assuming all advertised features come with a free local install.
This is an option to investigate for a library-wide image workflow. It is not a measured recommendation about output quality or compression ratios.
Protect the originals
Make a backup of uploads before bulk compression or resizing. Confirm whether the selected tool preserves originals, how much additional storage it uses and how to restore them. A file backup taken after destructive processing may no longer contain the original photograph.
Run a small sample first. Include a detailed photo, an image with text and a transparent image if your site uses them. Compare appearance at the actual display sizes and inspect network delivery.
Avoid overlapping controls
A cache plugin may also provide image conversion or lazy loading. Choose one owner for each operation so one tool does not undo another's settings. Test galleries, sliders and above-the-fold images after changing delivery.
Review remote processing and CDN terms, especially for images that include people or private material. A local-processing route can reduce external transfer but still requires host resources and permissions.
After configuration, measure a real page again. Confirm the requested URL, transferred bytes, image dimensions and visual quality. Do not treat a dashboard's saved-bytes counter as proof of better user experience.
Official product documentation was checked on October 7, 2026. No compression benchmark or hands-on plugin test is claimed.
Sources & verification
Sources checked September 25, 2026. Documented behavior is distinct from hands-on testing.