User blog comment:Ducksoup/The Future of Infoboxes on Wikia/@comment-4088096-20150824221845/@comment-4088096-20150824231608

Currently the template serve images scaled down with 270px maximum width. And AFAIK there's no other way to alter the served image size. Changing CSS would only alter the displayed image size, not the actual image served. This is suboptimal, especially in high aspect ratio images where cropping or manual size control is needed.

Very wide image at 270px max width usually results in very small image. Very tall image at 270px max width usually results in very large image. Cropping with CSS would resolve the display issues, but the filesize is still huge.