A common mistake: uploading a huge image that is displayed very small.

The rule

An image should not be much larger than the space where it appears. There is no point uploading a 4000 px photo for a 300 px thumbnail.

Best practices

• Resize before uploading.
• Let WordPress generate its intermediate sizes and serve the right one for each location.

Exercise: find a heavy image displayed small on your site and replace it with a resized version.