General Image Optimizer options can be found in your XenForo Admin Control Panel → Setup → Options → [TH] Image optimizer. You can also navigate to options by going to Admin Control Panel → Content → Image optimizer → Options.
Optimize images when they’re uploaded - When this option is unchecked, images will be optimized via a cron that runs automatically. If this cron is unable to keep up with new images that are uploaded or causes server load issues it is recommended that you enable this option.
Log informational errors - When enabled, additional informational messages will be logged into your XenForo error log. It is recommended to disable this option after everything is configured.
Secret Key - The key shown is used to secure “th_imageoptimizer.php” which is used to render the image to some image optimization providers.
Disabled content types - Content types selected here will not have their images optimized. If none are selected any images uploaded within these content types will be optimized.