When adding images to the Media Library, the image size and quality is important for appropriate resolution in your content for both desktop and mobile viewing. A large image size can change the way the content behaves and make it very slow to render.
To avoid this issue here are some tips and tricks:
use a .jpg file type unless it is a transparent image (which must be .png)
Before uploading an image, we recommended resizing the file to q_75,c_scale,w_1400 (the height should automatically adjust)
For Pixel width we recommend to use a maximum width of 1400 px