WordPress Slow: Optimize Images and Use WebP

What this problem is

Pages feel slow because images are too large, uncompressed, or served in heavy formats.

Why it happens

• Large uploads straight from a phone or camera
• No compression or no responsive image sizes
• PNG used where JPEG/WebP would be better

Prerequisites

• wp-admin access
• Backup (recommended) before bulk optimization

Diagnosis

1. Open a slow page and identify the largest images (browser DevTools or any speed test).
2. Confirm whether your theme generates multiple sizes (thumbnail/medium/large).
3. Check if WebP is already served by your host or a plugin.

Step-by-step (detailed)

1. Install an image optimization plugin (for example: ShortPixel, Imagify, Smush) or use your host tools.
2. Enable automatic optimization on upload.
3. Enable WebP generation and delivery (via picture tag or rewrite rules depending on the plugin).
4. Run a bulk optimization for existing media.
5. Re-test the page and confirm that the transferred image size is smaller.

Expected results

• Lower page weight and faster load time
• Better scores on mobile connections

What to do if it fails

• If images look blurry, adjust compression level to a higher quality setting.
• If WebP breaks images, disable WebP delivery and keep compression only.
• If CDN is used, purge CDN cache after changes.

Best practices

• Upload images at the maximum display size you need, not larger.
• Prefer WebP for photos; keep PNG for transparency when needed.
• Use lazy loading for long pages.