When SkipMimeTypeFromContent wasn't explicitly set the determination will always use the content. This will block the gui thread if the item is on a mounted remote file system such as sshfs or cifs as reading may take a while depending on network bandwith/latency and remote IO bandwith/latency. Supposedly a simple isSlow() and then using the SkipMimeTypeFromContent branch would help mitigate this. Alas, possibly a bit awkward since we currently don't have an enum value that'd represent "we'll do what feels sane" auto mode.