Properly optimised images can save many bytes of data. With optimised images, your website will load faster.
Search engine ranking will improve because of faster loading speed. Google started using site loading speed for SEO ranking in 2010 - http://goo.gl/V8Xx4m
You can check your page speed with this google tool: https://goo.gl/yG6ejW
Here is example of PageSpeed score for optimised and unoptimised web page:
According to surveys done by Akamai and Gomez.com , almost half of users expect a website to load in 2 seconds or less and they tend to abandon a website that isn’t loaded within 3 seconds 
When you install the Crush.pics app, it will go through all images and optimize them until it reaches 5 MB of images - which is FREE. After that you can subscribe to a plan and continue with optimization.
When you add new product images or new asset images, Crush.pics will automatically optimize it.
Crush.pics will also store your original images for 30 days, if you wish you can restore the originals at any time.
If you are not happy with the compression you can simply do a Batch Restore. It will restore all compressed images to the original. We keep backup for 30 days.
There is no quality loss with LOSSLESS compression, all images will be same as original. So your products, photographs or art will look as crisp as in the originals! Compression will go up to 30%
If you choose LOSSY compression, there will be small loss in quality but it's not visible to human eye. Compression will go up to 70%
After installing, if you choose AUTOMATIC mode, Crush.pics will go through all your Product images and queue them for compression. In FREE tier you have 5MB/month of free compression. After that you can purchase a plan and continue with compression.
After you purchase a plan, all asset images will be added to compression queue as well.
Also, any new image you add to products or assets will be added to queue automatically.