Web performance has been a huge focus of my engineering efforts on Rent.com and ApartmentGuide.com over the past year and a half while working at RentPath.

This was a fun and counter-intuitive conclusion that we came to and implemented in our websites after some deep performance investigations that I wrote about on the RentPath Engineering blog:

Watching the timeline with images, we realized that the Google Map tiles were being counted as the largest element, which was severely negatively affecting our LCP scores since they took so long to load — in Lighthouse, the LCP penalty is a factor of size plus load time.

And the conclusion of our work:

The end result was that increasing the size of our thumbnail images raised our performance score by reducing our LCP score. If you are thinking of web performance in straightforward terms like “shipping less data over the wire = faster”, this can be a very counter-intuitive result.

Original Post: We Increased our Lighthouse Score by 17 Points by Making Our Images Larger