The file sizes of images can greatly affect the total size of website pages and therefore negatively affect your website performance. Having a slow website not only discourages people from viewing your pages, it also hurts your website's search engine performance.
You can address this by reducing the size of images using image compression. Compression reduces the total file size of each image without affecting the quality of the image too much.
Image compression can be performed by many image editing applications, however online tools are also available to help you reduce file sizes.