If your images are big is size in MB's (megabytes), then it will affect the page load time of your website. So it is necessary that the page load time should be reduced. For this you need to properly optimize your images.

You can use image optimization tools like TinyPNG and Optimizilla in order to reduce the size of teh image without compromising on its quality.

Besides this, Giving the image an Alt text also comes under image optimization

I agree with you.

1. Name Your Images Descriptively and in Plain English
2. Optimize Your Alt Tags Intelligently
3. Strategize Your Image Dimensions and Product Angles
4. Reduce the File Sizes of Your Images
5. Know Which Image File Type to Use for the Right Situations
6. Know How To Handle Your Thumbnails
7. Use Image Site Maps
8. Beware of Your Decorative Images
9. Use Caution When Using Content Delivery Networks
10. Test Your Images!

You are looking for optimize images, then check those images that are heavy. After that, you need to work to compress them. After that, you should identify keywords related to your images and content, and then you can use those keywords with the help of an alt tag. This way, you can optimize images for SEO.