1
EWWW Image Optimizer Paid version Standard
Easy IO scales and converts images, including those in external CSS.
94feature score
WordPress Image Optimization Plugins with CSS background images
Also optimises or converts images used in CSS backgrounds. 6 of the 8 plugins we track include it.
2
Smush Paid version Pro
CDN and Next-Gen modules handle CSS background images; listed as a Pro capability.
92feature score
3
ShortPixel Image Optimizer Partial
CSS background images can be served from the CDN option, which consumes credits.
90feature score
4
Optimole Included
CSS background image lazy loading and replacement can be enabled for selected elements.
77feature score
5
Converter for Media Included
URL-level rewrites also cover images referenced in CSS.
74feature score
6
TinyPNG Partial
Only covered when the Apache .htaccess delivery method is used.
60feature score