Resize/nextgen-optimization.... Huh? All of these optimization settings can be very overwhelming if you're looking at them for the first time. Let's quickly go over these so you know exactly what each option does!
Optimization Settings
Resize/nextgen-optimize:
Allows you to add a "nextgen" image format (WEBP) as an alternate media source to take advantage of browsers supporting this format.
Resize/optimize:
Resizes and applies a compression algorithm (e.g. JPG compression) to reduce the image size.
Resize only:
Resizes the image to fit in the width/height needed for where it's being used.
Do not resize or optimize:
Only the original image is used, exactly as uploaded.