Teaser widget - images should be resized / downscaled
The teaser widget uses the images in the original upload size. If a user selects a big 5 MB image to use in a teaser - then this image is used.
The image should be resized/downscaled to be used in the teaser widget.
Agree with this as it can impact load time. Just need to make sure image quality isn’t lost though. Especially in cases where a large PNG might be uploaded and then is converted to JPEG which often results in it being blurry.
Marko Scholz commented
Every good CMS compresses the images before outputting graphics in order to reduce the network load.