How to serve scaled images and optimize images – GTmetrix, without using any plugins
Improving the score for Serve Scaled images and optimizing images to achieve better ratings at GTmetrix in fact isn’t that difficult. With some adjustment in the images sizes and photos quality we can massively improve the score, in fact, in most cases, we can achieve A or 100 for these constraints (provided there are no external images links your site is using via plugins or others).
If you are just building up your website, you can easily optimize all images (jpg or png) using TinyPNG. The free version allows up to 20 images of 5MB each.
Here are other tutorials to improve your GTmetrix Score: