Thumbnail settings: $wgGenerateThumbnailOnParse
Allow thumbnail rendering on page view.
Introduced in version:1.7.0 (r15342)
Removed in version:still in use
Allowed values:(boolean)
Default value:true

Details edit

Allow thumbnail rendering on page view. If this is false, a valid thumbnail URL is still outputted, but no file will be created at the target location. This may save some time if you have a thumb.php or 404 handler set up which is faster than the regular webserver(s).

Setting this to true is equivalent to setting the transformVia404 property in $wgLocalFileRepo and $wgForeignFileRepos to false.

See also edit