An oversized image or table on your page can greatly reduce your page's readability and disrupt its layout. It affects page loading and can also cause problems in printing, wasting natural resources.
That's why you should limit all your images and tables to a maximum of 800 pixels wide.
Some have said 800 pixels is too small, if you resized a large image you can't read the text - we think if you have an image that is large, then there must be reasons.
Also, if you are resizing in Photoshop you can easily resize the image and yet put the zoom out on a part that you want the reader to read (combining both options).