Thank you for using WP Smush. While the Smush plugin will compress images and ensure your images are not over a certain size it will not scale images to match the specific height and width requirements of your site.
If you are still getting a low grade on Google PageSpeed even after running Smush, it is probably because your images are not scaled for where they are being displayed. Scaling images before uploading them can be time-consuming but can save space and speed up load time. To fix this, first, you will need to determine what size your image should be. You can use the built-in developer tools in Chrome or Firefox to find what height and width your images are displaying at. Once you know how large the image should be, scale your images to this size with the WordPress image editor, Photoshop or any other editing software.
Tip: you may not need to scale each image individually. If the images are in your Media Library, you may be able to fix them with a plugin.
Hope this helps! Let us know if you have any other questions.
