Board Thread:Support Requests - Designing Your Wikia/@comment-9944069-20151106015619/@comment--20151106035914

The original one is a JPEG file which would indeed be smaller file size than that PNG file.

If you can, try finding that image as a JPEG or a JPG. If you can't find one, you can convert the one you have using a free online site that will convert images to another file type. You may try looking in Google here. As a warning though, there will be a quality drop when converting to a smaller file size :)