Serving scaled images is important! Here are some images that needed scaling on a client website.
And here is the before GTMetrix score:
Now, the images are then optimized so that instead of scaling them, they are the exact size displayed. We run GTMetrix again, and we find:
Now for the score improvement!
Note that image scaling is one of the metrics found on the GTMetrix score card. There are many more!
For example, under Page Speed:
And of course, there are others under the other tabs. Optimize them all, and you will have a beautifully optimized website.
Why so many tools? Everyone has a different idea about what "great" means. Our goal is to be "as great as possible" using all of these tools.
How much time does it take to optimize a website, anyway? That depends. You might be able to do it in a day, or two days. In some cases, it will take longer.