Report savings on all opportunities combined

TL;DR: I want to know your opinion about prediction model for Performance Score related to image optimization

I wanted to figure out the exact impact of image optimizations on Performance Score before implementing them.

I took the world’s top 500 websites (from Alexa) and ran performance analyses with Lighthouse and PageDetox (a diagnostic tool made by Uploadcare, a company I work at).

PageDetox fetched website images, optimized them, and calculated the differences in image weights and page-loading times (I used the same throttle settings as Lighthouse, and decreased derived load times by saved_bytes / speed).

From there, I tried to model the improvement in Performance Score by proportionally decreasing the weighted params used in the score calculations: FCP, FMP, SI, CPU, and TTI.

I understand that I have the two weak links in this model:

1. Load time improvement might easily fall to zero if JS rendering takes ages while even the largest images have already been loaded;
2. Linearly decreasing the Performance Score parameters may not be an exact fit.

But I think that (on average) the data I got is legit. Here is a raw data — https://docs.google.com/spreadsheets/d/1K1qUIPCm2ZOxwCW52Zu5oLo5p9r8xydEh5h97HF3eyU/edit?usp=sharing

What are your thoughts about this prediction model? Where do you see the room for improvement?

My final goal is to get proof to convince people (by estimating the value they get prior to investing any resources in the optimization) that image optimization is essential and affects business metrics.

p.s. If you are interested, I published an article about this model — https://blog.uploadcare.com/image-optimization-and-performance-score-23516ebdd31d. Though I’ve mentioned above everything related to the model.

[paulirish]

We’re not planning to calculate this number.

[rsedykh]

@patrickhulce so basically in the future Lighthouse report might say you exactly how much you can save by implementing opportunities? Nice! Until then, people can use pagedetox.com. 😃

(Right now I’m considering adding Lighthouse report to the mix so users can see savings + increase of Performance Score, but it will be more user-friendly for users to actually see it within Lighthouse).