How I optimized my SvelteKit website from 70 to 95+ on mobile Lighthouse tests

When I initially built this portfolio/blog website, my priority was getting it live quickly, so I didn't pay much attention to performance. The stack I used — SvelteKit and TailwindCSS — handled a good baseline but tools alone can't cover everything. Lighthouse desktop scores were about 95-98 but mobile scores were only around 65-80. The mobile tests are very harsh. They simulate a slow 4G network and a very throttled CPU. So many things that are negligible on desktop become prominent on mobile. I had to put in work to improve these things to make the mobile test scores better. I also wanted to expand my knowledge of website loading performance, so I decided to take on this project. And I finally achieved what I wanted. Now after all this work, my test scores are consistently 95+ on mobile and 100 on desktop. And I learned quite a few things along the way. With this post, I want to publish my journey and the things I learned. The topics will be varying from why I chose JPEG instead of