Any image loading, even images with a normally built-in handler like png, would cause all image format plugins to be loaded. This would even happen during application initialization because of built-in style and cursor images etc. The reason was that QImageReader would first query all plugins for their support of the given file suffix or format name, in order to allow custom plugins to override the built-in format handlers. However, image format plugins are required to register the format names they support in the plugin metadata (the plugin json file). So in order to support the override scenario, it is enough to check the suffix/format against the plugins' metadata, and if a match is found, to load and query the matching plugin(s). This commit implements that change, moving the querying of all other plugins to be done only if the suffix/format matches none of the built-in formats. Fixes: QTBUG-129330 Change-Id: I799df9c340d4d86316de77bff32fdbd75caffd5f Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>