Optimized images load faster and consume less cellular data.
Click View details to see each JPEG image that can be optimized. To pass the audit, set the compression level of each image to 85 or lower.
See Image Optimization to learn more about the topic in general.
Web services like TinyJPG can help automate the process of image optimization.
Lighthouse collects each JPEG image on the page, sets each image's compression level to 85, and then compares the original version with the compressed version. If the potential savings are 4KB or greater, Lighthouse includes the image in its report.